CLASS - XI PHYSICS

Question bank on kinematics( 1 mark questions)

Q1. Define frame of reference?Q2. Define displacement?Q3. What is the nature of position-time graph of a stationary object?Q4. What is the nature of position-time graph in uniform motion?Q5. What does the slope of position-time graph represent?Q6. What does the area under position-time graph represent?Q7. What does the area under velocity-time graph represent?Q8. What does the slope of velocity-time graph represent?Q9. Define relative velocity in one dimension?Q10. If an object goes from A to B and cover a distance of 20 cm then again go from B to A. then what is the total distance and total displacement of the object?Q11. If x=5t2 +7t+3m, then find velocity at t=2sec, where x is the displacement?Q12. What do you mean by vector quantity?Q13. What is difference between position and displacement vector?Q14. What is the statement of triangle law of vector addition?Q15. What is the statement of parallelogram law of vector addition?Q16. What do you mean by resolution of vectors?Q17. What do you mean by rectangular component of vectors?Q18. Define a projectile?Q19. Define trajectory?Q20. Give an example of motion of particle which has constant speed but have acceleration?

( 2 mark questions)Q1-If in case of motion displacement is directly proportional to the square of time elapsed, what do you think about its acceleration' Explain ,why?

Q2Which graph represents higher velocity and why?

x

t

Q3 An object is moving with constant velocity v along a straight line. What will be the shape of displacement-time graph if

(a)xo=-ve, v=+ve (b)x0=+ve v=-ve

Q4 The minutes hand of a wall clock is 10 cm long. Find its displacement and the distance covered from 12.00 noon to 12.30pm

Q5 A particle is thrown upwards. It attains a height h after 5 s and again after 9 s. What is the speed of the particle at height h?

Q6 Find the angle between two vectors P and Q if resultant of two vectors is given by R2=P2 +Q2 .

Q7 One of the rectangular components of a velocity of 60km/h is 30 km/h.Find the other rectangular component.

Q8 A car travels 20 km due north and then 35km in a direction 60o west of north. Find the magnitude and direction of resultant displacement of the car.

Q9 Find a unit vector parallel to the vector A=3 i+4 j+7 k.

Q10 Show that the maximum horizontal range of a projectile is four times the corresponding maximum height.

Q11 A train is moving due east with a velocity of 60km/h and a car is running due north with a velocity of 60km/h.What is the observed velocity of the car as felt by a passenger in the train.

Q12 Prove that A= I - 2J AND B=2i + j are mutually perpendicular to each other.

Q13 A swimmer can swim with velocity of 10 km/h with respect the water floing in a river with velocity of 5km/h. In what direction should he swim to reach the point on the other bank just opposite to hi starting point.?

QA14 Earth moves in circular orbit around the sun once every year with an orbital radius of 1,5x1011 m.

What is the acceleration of earth towards the centre f the sun?

Q15 Define uniform circular motion. Is it an accelerated motion ? If yes ,what is the direction of the acceleration?

( 3 mark questions)

Q.1 A ball is thrown vertically upward with a velocity of 20m/sec from top of a multistoried building. The height of a point from where the ball is thrown is 25 m from the ground. (i) how high the ball will rise? (ii) How long will it be before the ball hit the ground?

Q 2. show that the area under velocity –time graph of an object moving with constant acceleration in a straight line in a certain time interval is equal to the distance covered by the object in that interval.

Q 3. use integration technique to prove that the distance travelled in nth second,

Snth = u+ a2 (2n−1)

Q 4. Define centripetal acceleration. Derive an expression for the centripetal acceleration of a particle moving with uniform speed v along a circular path of radius r. Discuss the direction of this acceleration.

Q 5. A man can swim with a speed of 4km/h in a still water. How long does he take to cross the river 1km wide, if the river flows steadily at 3km/h and he makes his stroke normal to the water current? How far from the river does he go, when he reaches the other bank?

Q6.A stone is tied to the end of a string 80cm along is whirled in a horizontal circle with a constant speed. If the stone makes14 revolutions in 25 secs, what is the magnitude and direction of a acceleration of the stone?

Q7. The resultant of two vectors P and Q is perpendicular to P and its magnitude is half that of Q. What is the angle between vectors P and Q?

Q8.Draw Velocity time graph for uniformly accelerated motion . Show that slope of velocity v time graph gives acceleration of the body.

Q9.Define relative velocity of one object w.r.t another object draw position time graphs for two objects moving along straight line when their relative velocity is (i) Zero (ii) Positive (iii) Negative.

Q10. Two balls are thrown simultaneously , A vertically upward with speed of 20 m/s from the ground ,and B vertically downwards form a height of 40m with the same speed and along the same line of motion .At what points do the two balls collide? G= 9.8 m/s2 .

Q11.Define centripetal acceleration & hence derive expression for it?

(5 mark questions)Q.1Define relative velocity. Explain in detail the concept of relative velocity. Four particles A,B,C &D are situated at the corners of a square ABCD of side ‘ a’ at t=0. Each of the particle moves with constant speed v. A always has its velocity along AB, B along BC, C along CD and D along DA. At what time will the particles meet each other?

Q.2 What do you mean by a projectile? Show that the path of a projectile is always parabolic in nature. For a projectile thrown at an angle ‘Ɵ’ with hprozontal and velocity u, find:

i) Time of flight

ii) Horizontal range &

ii Maximum height attained.

Q3. (a)Derive the following Equations of motion for uniformly accelerated motion from velocity time graph.

i) v=u+ at ii) s = ut +1/2 at2 iii) v2=u2+2as

(b)Also write equations for uniform motion.

Q 4(a)What is resolution of vectors. Explain the phenomena of pedaling of bicycle with the help of resolution of vectors.

(b) Find the angle of projection for which horizontal range and max. height are equal.

Q.5(a) Derive the position vector ‘r ‘in three dimensions,

r=x i+ y j+z k with the help of vector addition.

(b) Find the resultant of two equal vectors if their resultant is equal to either of the two.

Topic: - Laws of Motion Questions carrying 1 mark1. What is the unit of coefficient of friction? 2. Name the factor on which coefficient of friction depends? 3. What provides the centripetal force to a car taking a turn on a level road? 4. What is the direction of the acceleration of an object that is slowing down while heading northward?5. What is the acceleration of an object thrown straight up in the air, near the surface of the earth, at the very top of its flight?6. What is the direction of the net force acting on an object that is moving in a circle with constant speed?7. Is it possible to round a corner with constant velocity? Explain. 8. Automobile tyres are generally provided with irregular projections over their surfaces. Why?9. Why the mud from moving wheels of vehicle fly off tangentially?10. A body of mass m is moving on a horizontal table with constant velocity. What is the force on the table?11. Rocket works on which principle of conservation?12. You can move a brick easily by pushing it with your foot on a smooth floor , but if you kick it then your foot is hurt. Why?13. Why does a swimmer push the water backwards?14. Action and reaction are equal in magnitude and opposite in direction , then why do not they cancel /balance each other?15. Why do we pull the rope downwards for climbing up?16. Mention a factor on which coefficient of friction depends.17. Carts with rubber tyres are easier to pull than those with iron tyres. Why?18. Give a relation for impulse in scalar form.19. It is easier to catch a table tennis ball, then a cricket ball, even when both are moving with same velocity. Why?20. What is gravitational unit of force? Questions carrying 2 marks21. Give the magnitude and direction of the net force acting on(a) A drop of rain falling down with constant speed.(b) A kite skillfully held stationary in the sky. 22. According to Newton' s Second Law, more massive objects tend to be harder to accelerate. Why then do all objects, regardless of mass accelerate at the same rate when in free fall?23. Two blocks of masses m1, m2 are connected by light spring on a smooth horizontal surface. The two masses are pulled apart and then released. Prove that the ratio of their acceleration is inversely proportional to their masses. 24. A shell of mass 0.020kg is fired by a gun of mass 100kg. If the muzzle speed of the shell is 80m/s, what is the recoil speed of the gun? 25. Suppose that there is a first piece of rock which weighs 5 Newton. Force F is applied to this first piece of rock and it produces an acceleration of a. Now if there is a second piece of rock. What force need to be applied to the second piece of rock to produce acceleration of 10a. Mass of both the pieces of rock is same. 26. Consider the problem on that on the object having initial mass of 4 kg. Two forces are acting on the object. Force F1 equal to 10 Newton and another force F2 equal to 4 Newton. Direction of F2 is opposite to the direction of F1. Suppose that mass of the object decreases from 4 kg to 2 kg when forces are applied to the object. Calculate the acceleration of the object. 27. Consider a person standing on a scale in an elevator. Will an accurate scale read more than, less than, or equal to the weight of the person when the elevator is slowing down while moving downwards? Explain.28. Show that it is easier to pull a lawn roller than to push it.

29. Explain the need of banking of tracks.30. Why frictional force gets increased when two surfaces in contact are polished beyond certain limit?31. Show that Newton’s first law of motion is contained in Newton’s second law of motion.32. If action and reaction are always equal and opposite, explain how a cart drawn by a horse moves forward?33. Why is friction called self adjusting force?34. Explain why is it difficult to move a cycle along a road with its brakes on?35. A thief jumps from the upper storey of house with a load on his back. What is the force of the load on his back when the thief is in air ?

Questions carrying 3 marks36. State Newton’s Second Law of Motion. Derive a mathematical formula to calculate force if mass remains constant. Prove that it contains Newton’s first law.37. State the law of conservation of momentum. Prove it by using second law of motion. Give two situations where the linear momentum remains constant.38. Two unequal masses m1 and m2 (m2>m1) are connected by a string which passes over frictionless pulley. Find the tension in the string and acceleration of masses.39. A train runs along an unbanked circular bend of radius 30m at a speed of 54km/hr. The mass of the train is 106kg. What provides the necessary centripetal force required for this purpose, the engine or the rails? What is the angle of banking required to prevent wearing out of the rail? 40. Define coefficient of static friction and dynamic friction. Derive expression for the acceleration of the body sliding on a horizontal plane having coefficient of friction µk. 41. What are concurrent forces? Prove that under the action of three concurrent forces F1,F2, and F3, a body will be in equilibrium, when F1+F2+F3= 0.42. Derive a relation for the velocity at the lowest point and the highest point for looping the loop of a vertical circle. 43. Prove that Newton’s second law is the real law of motion.44.Define coefficient of friction angle of friction and hence derive a relation between them.45.

m1 T1 m2 T2 m3Three blocks are connected as shown above and are on a horizontal frictionless table. They are pulled to right with a force F=50 N . if m1= 5kg , m2=10kg and m3=15kg, calculate tensions T1 and T2.

Questions carrying 5 marks 46. (a) Define impulse. State its S.I. unit?(b) State and prove impulse-momentum theorem? 47. Derive an expression for the apparent weight of a person in a lift when (a) the lift is moving up with acceleration (b) moving down with acceleration (c) moving up with acceleration (d) moving down with deceleration (e) moving up or down with constant velocity.48. What is Banking of roads? Derive an expression for the maximum possible speed on a road of banking angle Θ and coefficient of friction µ between the roads and the tyres.49. (a) An object is moving on a circular path in horizontal plane. Radius of path is constant and speed is v. Deduce expression for centripetal acceleration.(b) Obtain an expression for the centripetal force required to make a body of mass m, moving with a velocity v around a circular path of radius r.50 (a). Find an expression for velocity of recoil of gun.(b)A hunter has a machine gun that can fire 50g bullets with a velocity of 150ms-1. A 60kg tiger springs at him with a velocity of 10 ms-1. How many bullets must the hunter fire into the target so as to stop him in his track? 51. (a). Define angle of friction and coefficient of friction.(b). A bullet of mass 0.01kg is fired horizontally into a 4kg wooden block at rest on a horizontal surface. The coefficient of kinetic friction between the block and the surface is 0.25. The bullet remains

embedded in the block and the combination moves 20m before coming to rest. With what speed did the bullet strike the block?

MEASUREMENT AND WORK, ENERGY & POWER:

1 MARK QUESTIONS:

1. Is work done a scalar or a vector?2. When is work said to be 1 joule?3. What is the amount of work done by the earth’s Gravitational force in keeping the moon in a

circular orbit around the earth?4. Give two examples from daily life where according to physics work done is Zero?5. Force & displacement, both are vectors. Yet their product work is a scalar quantity?6. Can acceleration be produced without doing any work? Give example.7. Under what condition is the work done by a force (a) Positive (b) Negative?8. Under what condition is the work done by a force Maximum?9. Under what condition is the work done by a force Zero in spite of displacement being taking

place?10. What is the work done by the tension in the string of a simple pendulum?11. In a game of tug of war, what is the work done and by whom?12. A particle of mass m has momentum P. What is its kinetic energy?13. If mechanical work is done on a body, will its K.E. increase or decrease?14. What is the source of K.E. of a falling rain drop?15. What is the source of K.E. of the blood coming out of the barrel of the rifle?16. With what type of force is the potential energy associated?17. Define force constant. What is its SI unit?18. Can K.E. of a body be negative or positive?19. Define power and its SI unit?20. Calculate the power of a train in Watts which lifts a mass of 100 Kg to a height of 10 m in 20 s.

Two marks questions:

1. Show that work may be expressed as scalar product of force and displacement.2. What is the work done by centripetal force? Explain?3. Calculate the work done by a car against gravity in moving along a straight highway. The mass of

the car is 400 Kg and the distance moved is 2 m.4. Show that the instantaneous power is given by dot product of force and velocity?5. A body is moved along a closed loop. Is the work done in moving the body necessarily Zero? If

not, state the conditions under which the work done over a closed path is always Zero?6. Find expression for Gravitational potential energy of mass m situated at a height h from the

surface of earth?7. Calculate the power of a motor which is capable of raising 2000 L of water in 5 min from a well

120 m deep.8. Two bodies of unequal masses have same linear momentum. Which one have greater K.E. and

why?9. Define atomic mass unit. Find its value?10. Express a light year in terms of astronomical unit.

11. Give the correctness of relation v2 – u2 = 2as by method of dimension.12. What are random errors? How is their effect eliminated?13. What do we mean by absolute error and relative error of a measurement?14. The radius of a solid sphere is measured to be 11.24 cm. What is the surface area of the sphere

to appropriate significant figure?15. Find the Dimensional formula of (a) Gravitational Constant (b) Plank Constant

THREE MARK QUESTIONS:

1. Describe the parallax method to measure the distance of a planet from the earth.2. Time period (T) of the simple pendulum may depend upon its mass m, length l and acceleration

due to gravity g . Find an expression for time period T by method of Dimension.3. A steel ball of radius r is allowed to fall under gravity through a viscous liquid of coefficient of

viscosity ἠ. After some time the ball attains a constant velocity v. The terminal velocity depends upon (a) weight of the ball mg (b) the coefficient of viscosity ἠ (c) the radius of the ball r. By method of dimension determine the relation expressing relative velocity.

4. A small bucket containing water is rotating in a vertical circle. Obtain a expression for minimum speed of bucket so that the water does not spill even at the highest point during its motion in a vertical circle.

5. By the method of dimensions, find the value of acceleration of 8 m/s2 in to km/hr2.6. Define elastic and inelastic collisions. A bullet is fired into a block of wood. It gets totally

embedded in it and the system moves together as one entity. State what happens to the initial kinetic energy and linear momentum of the bullet.

7. Prove that in an elastic collision in one dimension, the relative velocity of approach before impact is equal to the relative velocity of separation after impact.

8. Prove that the total mechanical energy of a freely falling body is always constant. Draw a graph showing variation of P.E., K.E. and total energy.

9. Show that the coefficient of restitution for one dimensional elastic collision is equal to 1.10. A bullet of mass 20 g is moving with speed of 150 m/s. It strikes a target and is brought to rest

after piercing 10 cm in to it. Calculate the average force of resistance offered by the target.FIVE MARK QUESTIONS:

1. State the principle of conservation of energy and show that this principle is valid in case of a freely falling body.

2. What is two dimensional elastic collision? Discuss collision of two bodies in two dimensions. Deduce from it the velocities of bodies in one dimension.

3. What is the difference between work and energy? An electric motor is used to lift an elevator and its load (1500 kg) to a height of 20 m. the time taken for the job is 20. The efficiency of the motor is 75%.(a) What is the work done(b) What is the rate at which the work is done?(c) At what rate is the energy supplied to the motor?

4. (a)Two blocks of wood A and B are coupled by a spring. They are placed on a frictionless table. The spring is stretched and released. Show the following relation K.E of A /K.E. of B =MB / MA

(b) A ball is dropped from rest from a height of 12 m. If it loses 25% of K.E. on striking the ground, What is the height to which it bounces?

5. What do we mean by conservative and neoconservative forces? Explain the various properties of conservative force and show that gravitational force is a conservative force.

TOPIC: ROTATIONAL MOTION AND MOMENT OF INERTIA

SECTION: A (1 MARK)

1. Define angular momentum and give its SI unit.

2. State work energy theorem for rotational motion

3. Can a body in translatory motion have angular momentum?

4. Is it possible to open pen cap with one figure? Why?

5. Calculate angular velocity of ‘Hour Hand’ of clock.

6. Why is it easier to balance a bicycle in motion?

7. Why do you prefer to use a wrench with a long arm?

8. What happens to duration of day night when tall buildings are constructed on the earth?

9. Why ships which have been emptied of Cargo are filled with the ballast?

10. A Rifle barrel has a spiral groove which imparts spin to the bullet. Why?

11. If one of the particles is heavier than the other, to which will their centre of mass shift?

12. Can centre of mass of a body coincide with geometrical centre of the body?

13. Which physical quantity is represented by a product of the moment of inertia and the angular

velocity?

14. What is the angle between A and B , if A and B denote the adjacent sides of a parallelogram

drawn from a point and the area of parallelogram is 12

AB.

15. Which component of linear momentum does not contribute to angular momentum?

16. A disc of metal is melted and recast in the form of solid sphere. What will happen to the moment of

inertia about a vertical axis passing through the centre?

17. What is rotational analogue of mass of body?

18. What are factors on which moment of inertia depend upon?

19. Is radius of gyration of a body constant quantity?

20. Is the angular momentum of a system always conserved? If no, under what condition is it

conserved?

SECTION: B (2 MARKS)

1. A body projected into space explodes. What will be the nature of path of its core?

2. How does a diver manage to make somersaults in air?

3. A disc of mass M and radius R is rotating with angular velocity ω. If gently, two masses ‘m’ are

placed at a distance R/2 on either side of the axis, what will be its angular velocity?

4. What is the angular momentum with the projectile when it is at the highest point about an axis

through the point of projection?

5. Can a body in translatory motion have angular momentum? Explain.

6. Two circular discs A & B of the same mass and same thickness are made of two different metals

whose densities are ‘dA’ and ‘dB’ (dA> dB). Their moments of inertia about the axis passing

through their centres of gravity and perpendicular to their planes are IA and IB. Which is greater

IA or IB?

7. Two identical cylinders ‘run a race’ starting from rest at the top of inclined plane, one slides

without rolling and other rolls without slipping. Assuming that no mechanical energy is

dissipated in heat, which one will win?

8. Briefly explain motion of Centre of Mass of Earth Moon system.

9. Name the physical quantity corresponding to inertia in rotational motion. How is it calculated?

Give its units.

10. If earth were to shrink suddenly what would happen to the length of the day?

11. Prove the Kepler’s law, that the line joining the sun and the planet sweeps equal areas in equal

interval of time, using the angular momentum conservation with planet.

12. Two eggs of same size and appearance but one is boiled and another is raw. How will you

recognized them without breaking them?

13. The distance between the centres of carbon and oxygen atoms in Carbon Monoxide gas

molecules is 1.13Ȧ. Locate the centre of mass of the molecules relative to carbon atom.

14. Write the rotational analogue of the following physical quantities (a) Force (b) Mass.

15. What will be the effect on the duration of the day if whole ice on the poles melts?

SECTION: C(3 MARKS)

1. Calculate the power required by a force to turn a rigid body by some angle ‘ɵ’.

2. How much fraction of the Kinetic Energy of rolling is purely (a) Translational (b) Rotational?

3. State and prove work energy theorem for rotational motion.

4. If there are ‘n’ particles of masses m1, m2, ….mn distributed in space, write expressions for x, y

and z coordinates of Centre of Mass.

5. Three particles each of mass ‘m’ are placed at three corners of an equilateral triangle of length

‘l’. Find the position of centre of mass in terms of coordinates.

6. Find moment of inertia of a thin rod about an axis perpendicular to it and passing through its

mid-point.

7. Establish a relation between angular momentum and moment of inertia of a rigid body. Define

moment of inertia in terms of it.

8. Torques of equal magnitude is applied to a hollow cylinder and solid sphere, both having the

same mass and radius. The cylinder is free to rotate about its standard axis of symmetry, and

the sphere is free to rotate about an axis passing through its centre. Which of the two will

acquire a greater angular speed after a given time?

9. A tube of length ‘l’ is filled with a liquid of density ‘ρ’. Find the force experienced at one of its

edge if rotated about the other edge with an angular velocity ω.

10.

A

ω0

SECTION: D (5 MARKS QUESTION)

1. Define Centre of Mass. State the need of determining Centre of Mass. Given a uniform circular

disc of mass M & radius R. A circular disc of radius R/2 is cut from it such that its circumference

touches the centre of given disc. Find the position of centre of mass of the remaining disc.

2. State the theorem of parallel & perpendicular axis of moment of Inertia. Moment of Inertia of a

uniform circular ring about an axis passing through its centre and perpendicular to the plane of

the ring is MR2, where M is the mass of the ring & R is its radius. Using these theorems

determine moment of Inertia of the ring about

(i) Any diameter of ring

(ii) Any tangent in the plane of the ring

(iii) Any tangent perpendicular to the plane of ring.

3. State the condition of equilibrium of a body. A body is constrained to rotate about Z-axis only.

State necessary conditions for the equilibrium of the body. Show that the torque required to

rotate the body is given by τz = xFy - yFx

4. State Law of conservation of Angular momentum. A disc of Moment of Inertia I1 is rotating

about an axis with angular velocity ω1, another disc of Moment of Inertia I2 rotating with angular

velocity ω2 in the same sense are brought in contact, find the common angular velocity of the

system. Also find the loss in Kinetic Energy.

5. What do you mean by the rolling motion? A body is rolling on an inclined surface without

slipping. Show that the relation for acceleration of the body is given by

. C

R/2 .

A disc rotating about its axis with angular speed ω0 is

place lightly (without any translational push) on a

perfectly frictionless table. The radius of the disc is ‘R’.

What are the linear velocities of the points A, B and C

on the disc shown in figure? Will the disc roll in the

direction inclined?

a=g Sinθ

1+ k2

R2

Where symbols have their usual meanings.

A ring and a Disc of same mass & radius are allowed to roll on an inclined, out of the two which

one will reach the bottom first?

6. Define angular velocity & angular acceleration. Also write their SI units. Derive all three

equations for uniformly accelerated rotational motion i.e.

(i) ω = ω0 + αt

(ii) ɵ = ω0t + 12

αt2

(iii) ω2 = ω02 + 2αɵ

ω

Vcm vcm

O’ O’

a T1 T2 a

m1

m2

P

O

7. A body is rolling on a surface as shown in fig.

Taking O’ as centre of reference frame show that

kinetic energy of rolling motion is

K = 12

MVcm2 +

12

Icmω2 OR

K = 12

MVcm2(1+ k

2

R2 )

Where K is radius of gyration of the body

R

8. An inextensible string connecting two masses m1 and m2 is

passing over a disc shaped pulley of radius R and moment of

inertia I. For m2>m1 find

(a) acceleration of the system

(b) Tensions in the strings T1& T2

There is sufficient friction between string and pulley to have

its angular acceleration α = a/R

9. Define Torque and Angular momentum and establish relation between them. A flywheel of mass 500

Kg and diameter 1 m revolves about its axis. Its frequency of revolution is increased by 18 in 5 sec.

Calculate the torque required.

10. Define Moment of Inertia of rigid body. List out the factors on which it depends? Derive an

expression for (a) Kinetic Energy (b) Angular momentum (c) torque for a body having moment of inertia I

and angular velocity ω rotating about fixed axis.

GRAVITATION

VERY SHORT ANSWER TYPE QUESTION (OF ONE MARK)

1. Name the weakest and the strongest force in nature?2. What is parking orbit?3. What is the value of gravitational potential at infinity?4. What is the value of escape velocity from the surface of earth?5. What is the reason for absence of atmosphere in some planets?6. As a spacecraft moves from surface of earth to the moon, how does its weight vary?7. What is the value of gravitational field at a point inside a spherical shell?8. What is the basis for the second law of Kepler?9. What does spring balance measure: mass or weight?10. What is the value of orbital velocity for a satellite orbiting close to the surface of earth?11. If the earth stops rotating about its own axis, what is the effect on the value of g on the surface

of earth?12. What is the value of time period of a geostationary satellite?13. What will be the value of time period of a simple pendulum in an artificial satellite?14. If the polar ice caps on the earth melt, how will the length of the day be affected?15. Two artificial satellite, one close to the surface and other away are revolving around the earth,

which has larger speed?16. How does the orbital velocity of a satellite depends on the mass of the satellite?17. What is the condition for a uniform spherical mass to be a black hole?18. Name the satellite used for TV and Radio broadcast?19. Which is greater-the attraction of earth for 1kg mass or attraction of 1kg mass for earth?20. Why do you feel giddy while moving on a merry-go-round?

SHORT ANSWER TYPE QUESTION (OF TWO MARKS)1. A body weighs 63N on the surface of earth. What is the gravitational force on it due to the earth at a height equal to half the radius of earth?2. Assuming the earth to be a sphere of uniform mass density ,how much would a body weigh half way down to the centre of the earth if it weighed 250N on the surface?3. What is geostationary satellite? What are the condition for a satellite to become the geostationary satellite?4. The radii of two planets are R and 2R respectively and their densities d and d/2 respectively. What is the ratio of acceleration due to gravity at their surface?

5.Why is the weight of a body at the poles more than the weight at the equator? Explain.6.What is the maximum value of potential energy that can a heavenly body? Give the general expression for potential energy of an object near the surface of earth.7.What happens to a body when it is projected vertically upwards from the surface of earth with a speed of 11200m/s,andwhy? Compare escape speeds for two planets of masses M and 4Mand radii 2R and R respectively?8.The time period of the satellite of the earth is 5hours.If the separation between the earth and satellite is increased to 4 times the previous value,than what will be the new time period of the satellite?9. Mention the conditions under which the weight of a person can become zero?10. What would happen if the force of gravity were to disappear suddenly?11. What is acceleration due to gravity? Establish relation between g and G?12. State two point of difference and similarity between the gravitational force and electrostatic force?13. What is gravitation? State universal law of Gravitation?14.The distances of two planets from the sun are 1012 and 1010 meters respectively. What is the ratio of periods of these two planets?15.What do you mean by Intensity or strength of gravitational field ?Is it a vector or scalar quantity.give its unit and dimensions.

SHORT ANSWER TYPE QUESTION(OF THREE MARKS)

1. State and explain the Kepler’s laws of planetary motion. Name the physical quantities which remain constant during the planetary motion?2. Find the potential energy of a system of four particles placed at the vertices of a square of side l. Also obtain the potential at the centre of the square?3. A 400kg satellite is in the circular orbit of radius 2RE about the earth. How much energy is required to transfer it to a circular orbit of radius 4RE? What are the changes in the kinetic and potential energy?4. Find the percentage decrease in the weight of a body when it is taken 16km below the surface of earth. Take radius of earth as 6400km.5. Find the height from the surface of earth at which weight of a body of mass m will be reduced by 36%of its weight on the surface. Take radius of earth as 6400km.6. What do you mean by intensity or strength of gravitational field? Prove that the intensity of gravitational field of earth at any point is equal to acceleration due to gravity at that point.7. What do you mean by acceleration due to gravity? Establish relation between g and G.8. Find the expression of total energy of a satellite revolving around the surface of earth. What is the significance of negative sign in the expression?9. What are geostationary satellites? Calculate the height of the orbit of a geostationary satellite.10. Calculate the escape speed for an atmospheric particle 1600 km above the earth’s surface, given that the radius of the earth is 6400 km and acceleration due to gravity on the surface of earth is 9.8 ms-2.

LONG ANSWER TYPE QUESTION (OF FIVE MARKS)

1. Define escape velocity. Derive an expression for the escape velocity of an object from the surface of the earth. Does it depend on the location from where the object is projected?2. What do you mean by acceleration due to gravity? Discuss its variation with depth and height.3. What do you mean by gravitational potential energy of a body? Derive an expression for the gravitational potential energy of a body of mass m located at a distance r from centre of the earth?

4. Define orbital velocity and time period of a Satellite. Derive an expression for orbital velocity and time period of a Satellite orbiting very close to the surface of Earth and hence find the ratio of the orbital velocity and escape velocity?5. State Kepler’s laws of planetary motion and hence deduce Newton’s law of gravitation from Kepler’s law of periods.

PROPERTIES OF BULK MATTER1 Marks Questions

Q1. Why are springs made of steel and not of copper?

Q2.Young’s modulus of wire of length L and radius r is Y. If the length is reduced to L/2 and radius to r/4, what will be its Young’s modulus?

Q3. Which is more elastic water or air?

Q4.What is the value of modulus of rigidity for an incompressible liquid?

Q5. Why are electric poles given hollow structure?

Q6. What is the value of surface tension at critical temperature?

Q7.Why is it difficult to stop bleeding from a cut in human body at high altitudes?

Q8. Mention two applications of Stoke’s law.

Q9. Fog particles appear suspended in the atmosphere , give reason.

Q10. A small sphere is dropped from rest into a viscous liquid. Draw its velocity time graph, also indicate the terminal velocity on the graph.

Q11. Write down the following liquids in increasing order of surface tension:

a) Water b) Mercury c )Soap solution

Q12. Why do air bubbles move in upward direction?

Q13. Explain why the blood pressure in humans is greater at the feet than at the brain?

Q14. What is the range for Reynolds number for the streamline motion of liquid?

Q15. Why do the boat moving parallel to each other attract each other?

Q16. Why two streamlines cannot cross each other?

Q17. Which fundamental laws form the basis of equation of continuity?

Q18. State the principle involved in the flight of aero plane.

Q19. Why is it easier to swim in sea water than in river water?

Q20. What is value of Young’s modulus for a perfect rigid body?

2 Marks Questions

Q1 state and prove equation of continuity.

Q2 On the basis of stress-strain curve differentiate between ductile and brittle material.

Q3 Explain Magnus effect with the help of diagram.

Q4 What do you mean by compressibility. Why are solids least compressible and gases most .

Q5 Distinguish between stream line flow and turbulent flow of liquid

Q6 At what speed will the velocity head of steam of water be equal to 40cm

Q7 Can Bernoulli’s equation be used to describe the rapid flow of water through a river ? Explain.

Q8 why does an object entering the earth’s atmosphere at high speed catch fire.

Q9 Define angle of contact of a liquid with a solid surface on what factors does it depend.

Q10 A square plate of 0.10m side moves parallel to another plate with a relative velocity of 0. 10m/s both the plates being immersed in water, if the viscous force is 2×10-3 N and coefficient of viscosity of water is 1×10-3 Pascal sec. What is the separation between the two plates?

Q11. The spherical raindrops of equal size are falling vertically through air with a terminal velocity of o.1 m/s. what would be the terminal velocity if the drops were to coalesce to form a single large drop?

Q12. Define surface tension mathematically. What is its S. I. unit? Write its dimensional formula.

Q13. What is the total potential energy of a soap film formed on a frame of area 6×10-4 m2 , given surface tension of soap solution is 0.028N/m.

Q14. Water is depressed in a glass tube bore coated with paraffin wax. why?

Q15. A large soap bubble is formed at one end of a narrow bore tube and a small one at the other end. Which one will grow at the expense of the other. Give reason too.

3 Marks Questions

Q1 State Pascal’s law . Using this law explain the working of hydraulic brakes

Q2 State and prove stokes law.

Q3 Define terminal velocity and derive its expression

Q4 What is the pressure inside the drop of mercury of radius 3mm at room temperature surface tension of mercury at that temperature is 4.65x10-1 N/m atmosphere pressure 1.01x 105 pa. Also give the excess pressure inside the drop.

Q5 (i) What is the largest average velocity of blood flow in an artery of radius 2x10-3 m .if the flow must remain laminar?

(ii)What is the corresponding flow rate? (take η= 2.08x10-3Pa-s)

Q6 Explain the following

(1) Concrete beam used in large buildings have greater depth than breadth

(2) Load bearing bars are generally made in I sections.

(3) Pillar with distrusted ends is preferred over a pillar with rounded ends.

Q7 (i) explain the role of detergent in washing of clothes

(ii) Hydrostatic pressure is a scalar quantity even though pressure is force/area

(iii) A drop of liquid under no external forces is always spherical

Q8 A plane is in level flight at constant speed and each of its two wings has an area of 25m2 if the speed of air is 180km/h over the lower wing surface determine the plane’s mass take air density to be 1kg/m3 and g=9.8m/s2.

Q9Write the Bernoulli theorem in terms of pressure head, gravitational head and velocity head . What will be the expression for horizontal flow of liquid during a certain windstorm light roof may be blown off?

Q10 (1) What is the effect of temperature on

(a) Viscosity of liquid (b) Surface tension of a liquid (c)viscosity of gases

(2) which is more viscous honey or water and why?

5 Marks Questions

1.(a) State and prove Bernoulli’s theorem.

(b) Write any two limitations and applications of this theorem.

Q2. (a) What is meant by capillarity?

(b) Derive ascent formula.

© Why does liquid not flow through a tube of insufficient length?

Q3. (a) Derive an expression for the excess pressure in a soap bubble.

(b) Explain what determines the shape of a a liquid meniscus in a narrow tube.

Q4. Discuss stress/ strain graph for a loaded steel wire and hence explain the following terms:

(a) Elastic limit (b)Yield point ( c)Permanent set (d)Tensile strength

Q5. (a) Name a device used to measure the rate of flow of a liquid through a pipe.

(b) State the principle on which it works. ( c) Describe its construction and working.

Q6. (a) Establish the relation between surface tension and surface energy. (b) Two wires of diameter 0.25 cm one made of steel and the other made of brass are loaded as shown in the figure. The unloaded

length of steel wire is 1.5 m and that of brass is 1.0 m. Compute the elongation of the steel and the brass wire.

1.5 m(steel)

4.0 kg

1.0 m(brass)

6.0 kg

1. Thermal properties of matter

2. Thermodynamics

3. Kinetic theory of gases

Section A Each question carry one mark.

1. Given Samples of 1 cm3 of Hydrogen and 1 cm3 of oxygen, both at N. T. P. which sample has a larger number of molecules?2. State the law of equi-partition of energy? 3. On what factors, does the average kinetic energy of gas molecules depend? 4. What is the relation between pressure and kinetic energy of gas? 5. Why is mercury used in making thermometers? 6. Show the variation of specific heat at constant pressure with temperature? 7. Two thermometers are constructed in the same way except that one has a spherical bulb and the other an elongated cylindrical bulb. Which one will response quickly to temperature change?8. Define triple point of water? 9. Why the clock pendulums are made of invar, a material of low value of coefficient of linear expansion?10. Why is temperature gradient required for flow of heat from one body to another? 11. If a body has infinite heat capacity? What does it signify? 12. Why is latent heat of vaporization of a material greater than that of latent heat of fusion?13. Draw a P – V diagram for Liquid and gas at various temperatures showing critical point?14. On a winter night, you feel warmer when clouds cover the sky than when sky is clear. Why?15. If a body is heated from 270 C to 9270C then what will be the ratio of energies of radiation emitted?16. If the temperature of the sun is doubled, the rate of energy received on each will increases by what factor?

17. Can you design heat energy of 100% efficiency? 18. Draw a p – v diagram for isothermal and adiabatic expansion? 19. State zeroth law of thermodynamics? 20. Differentiate between isothermal and adiabatic process?

Section B Each question carry two marks.

1. The earth without its atmosphere would be inhospitably cold. Explain Why?2. Calculate the degree of freedom for monatomic, diatomic and triatomic gas? 3. A thermometer has wrong calibration. It reads the melting point of ice as – 100C. It reads 600C in place of 500C. What is the temperature of boiling point of water on the scale?4. If the volume of block of metal changes by 0.12% when it is heated through 200C. What is the co-efficient of linear expansion of the metal?5. A ball is dropped on a floor from a height of 2cm. After the collision, it rises up to a height of 1.5m. Assuming that 40% of mechanical energy lost goes to thermal energy into the ball. Calculate the rise in temperature of the ball in thecollision. Specific heat capacity of the ball is 800J/k. Take g = 10m/s26. A 0.20 Kg aluminum block at 800C is dropped in a copper calorimeter of mass 0.05 Kg containing 200 cm3 of ethyl alcohol at 200C. What is the final temperature of the mixture? Given Density of ethyl alcohol = 0.81 g | cm3 ; specific heat of ethyl alcohol = 0.6 cal | g | 0C ; specific heat of copper = 0.094 cal |g | 0C, specific heat of Al = 0.22 cal | g | 0C?7. Show that CP - CV = R Where [CP = specific heat at constant pressure; CV = specific heat at constant volume and R = Universal Gas constant] for an ideal gas?8. From what height should a piece of ice fall so that it completely melts? Only one – quarter of heat produced is absorbed by the ice. Given latent heat of ice is 3.4 × 105 J | Kg and acceleration due to gravity, g = 10m | s2?9. Two rods A and B are of equal length. Each rod has its ends at temperatures T1 and T2. What is the condition that will ensure equal rates of flow of heat through the rods A and B?10. Animals in the forest find shelter from cold in holes in the snow. Why? 11. The tile floor feels colder than the wooden floor even though both floor materials are at same temperature. Why?12. A Carnot engine absorb 6×105 cal at 2270c calculate work done per cycle by the engine if it sink is at 1270c?13.A refrigerator placed in a room at 300 K has inside temperature 264K. How many calories of heat shall be delivered to the room for each 1 K cal of energy consumed by the refrigerator, ideally?14. If the door of a refrigerator is kept open in a room, will it make the room warm or cool? Why?15. State first law of thermodynamics and apply this law to isochoric and isobaric process.

Section C Each question carries three marks.

1. If half mole of helium is contained in a container at S. T. P. How much heat energy is needed to double the pressure of the gas, keeping the volume of the gas constant? Given specific heat of gas = 3J | g |K.2. Five moles of an ideal gas are taken in a Carnot engine working between 1000C and 300C. The useful work done in 1 cycle is 420J. Calculate the ratio of the volume of the gas at the end and beginning of the isothermal expansion?3. Calculate difference in efficiency of a Carnot energy working between:- 1) 400K and 350K 2) 350K and 300K.4. One kilogram molecule of a gas at 400k expands isothermally until its volume is doubled. Find the amount of work done and heat produced?5. How do you derive Newton’s law of cooling from Stefan’s law? 6. Define the terms reflectance, absorptance and transmittance. How are they related?7. Differentiate between conduction, convection and radiation? 8. What is Mean free path? Derive an expression for it.

9. Derive an expression for work done during isothermal process.Section D Each question carry five marks.1.(a) What are the basic assumptions of kinetic theory of gases? On their basis derive an expression for the pressure exerted by an ideal gas.

.(b)At what temp is r.m.s of an atom in an argon gas cylinder is equal to the rms speed of helium gas atom at -20oC.Atomic mass of argon =39.9u and that of helium =4u. Hint v=(3RT/M)1/2

2. (a) Prove that ɑ=β/2=γ/3.Where the symbols have their usual meanings in thermal expansion. (b)Brass wire 1.8m long at 270C is held taut with little tension between two rigid supports. If the wire is cooled to a temperature of -390C, what is the tension developed in the wire, if its diameter is 2.0mm? Coefficient of linear expansion of brass is 2.0 X10-50C-1,Youngs modulus of brass 0.91 X 1011Pa. Hint ∆l=lα(T2-T1),stress=strain x youngs modulus.

3. (a)What is Carnot engine? Derive an expression for efficiency of Carnot engine. (b) A steam engine delivers 5.4 X 108J of work and services 3.6 X 109J of heat from its boiler. What is efficiency of the engine? How much heat is wasted to the sink?4. (a). Discuss briefly energy distribution of a black body radiation. Hence deduce Wien’s displacement law?(b)The spectral energy distribution of the sun has maximum at 4753A0.If the temp of sun 6050K.What is temp of star for which this maximum is at 9506A0? Hint λm=b/T.5. (a)On what factors does the rate of heat conduction in a metallic rod in the steady state depend? Write the necessary expression and hence define the coefficient of thermal conductivity. Write its SI unit. (b). A room has a 4m x 4m x10cm concrete roof (K1 = 1.26w|m|0C). At some instant, the temperature outside is 460C and inside is 320C. (1) Calculate amount of heat flowing per second into the room through the roof. (2) If bricks (K2 – 0.56w |m|0c) of thickness 7.5cm are laid down on roof, calculate the new rate of heat flow under the same temperature conditions?

Waves and Oscillations

(1 marks questions)

1. Which of the following relationships between the acceleration ‘a’ and the displacement ‘x’ of a particle involve simple harmonic motion?(a) a=0.7x (b) a=-200x2 (c) a = -10x (d) a=100x3

2. Can a motion be periodic and not simple harmonic? If your answer is yes, give an example and if

not, explain why?

3. A girl is swinging in the sitting position. How will the period of the swing change if she stands up?

4. The maximum velocity of a particle, executing S.H.M with amplitude of 7mm is 4.4 m/s. What is the period of oscillation?

5. Why the longitudinal wave are also called pressure waves?

6. How does the frequency of a tuning fork change, when the temperature is increased?7. An organ pipe emits a fundamental node of a frequency 128Hz. On blowing into it more strongly

it produces the first overtone of the frequency 384Hz. What is the type of pipe –Closed or Open?8. All harmonic are overtones but all overtones are not harmonic. How?

9. What is the factor on which pitch of a sound depends?10. Write the Newton’s formula of velocity of sound in air.11. Write the necessary correction in Newton’s formula for speed of sound in air by Laplace?12. Is speed of sound in air depends on pressure? Justify your answer?13. Give expression for beat frequency?14. State Doppler’s effect?15. Why stationary waves are called standing waves?16. Write the expression for fundamental frequency in an organ pipe open at one end?17. Write the expression of displacement in plane progressive wave?18. What is the phase difference between incident and reflected wave from the rigid and open

boundary?19. Mention two applications of dopller’s effect?20. What effect on the time period of simple pendulum when it taken to the moon ?

(2 Marks questions)

1. At what points is the energy entirely kinetic and potential in S.H.M? What is the total distance

travelled by a body executing S.H.M in a time equal to its time period, if its amplitude is A?

2. A simple pendulum consisting of an inextensible length ‘l’ and mass ‘m’ is oscillating in a stationary

lift. The lift then accelerates upwards with a constant acceleration of 4.5 m/s 2. Write expression for

the time period of simple pendulum in two cases. Does the time period increase, decrease or remain

the same, when lift is accelerated upwards?

3. Does the function y = sin2ωt represent a periodic or a S.H.M? What is period of motion?4. All trigonometric functions are periodic, but only sine or cosine functions are used to define SHM.

Why?

5. A simple Harmonic Motion is represented by d2 xd t 2

+αx = 0. What is its time period?

6. The Length of a simple pendulum executing SHM is increased by 2.1%. What is the percentage

increase in the time period of the pendulum of increased length?

7. A simple Harmonic motion has an amplitude A and time period T. What is the time taken to travel from x = A to x = A/2.

8. An open organ pipe produces a note of frequency 5/2 Hz at 150C, calculate the length of pipe. Velocity of sound at 00C is 335 m/s.

9. An incident wave is represented by Y(x, t)=20sin(2x-4t).Write the expression for reflected wave (i) From a rigid boundary (ii) From an open boundary. 10. Explain why (i) in a sound wave a displacement node is a pressure antinode and vice- versa (ii) The shape of pulse gets- distorted during propagation in a dispersivemedium.

11. Derive an expression for apparent frequency when a source of sound approaches stationary observer with velocity Vs.

12. Derive Laplace correction in Newton’s formula in velocity of sound.

13. prove that beat frequency is the difference of individual frequency of components waves.

14. Give two differences between damped & undamped oscillations.

15. Explain the motion of simple pendulum is S.H.M.

(3 Marks Questions)1. The speed of longitudinal wave `V` in a given medium of density ρ is given by the formula, use this

formula to explain why the speed of sound in air.

(a) is independent at pressure

(b) increases with temperature and

(c) increases with humidity

2. Write any three characteristics of stationary waves.3. Show that the speed of sound in air increased by .61m/s for every 10 C rise of temperature.

4. Find the ratio of velocity of sound in hydrogen gas γ=7

5 to that in helium gas

γ=5

3 at the same temperature. Given that molecular weight of hydrogen and helium are 2 and 4

respectively.

5. The equation of a plane progressive wave is, y=10 sin 2 π (t−0.005x )where y & x are in cm & t in

second. Calculate the amplitude, frequency, wavelength & velocity of the wave.

6. Write displacement equation respecting the following condition obtained in SHM.

Amplitude = 0.01m

Frequency = 600Hz

Initial phase = π6

7. The amplitude of oscillations of two similar pendulums similar in all respect are 2cm & 5cm

respectively. Find the ratio of their energies of oscillations.

Ans.E1

E2

=¿

8. What is the condition to be satisfied by a mathematical relation between time and displacement to

describe a periodic motion?

9. A spring of force constant 1200N/m is mounted horizontal table. A mass of 3Kg is attached to the free end of the spring, pulled sideways to a distance of 2.0cm and released.

(i) What is the frequency of oscillation of the mass?

(ii) What is the maximum acceleration of the mass?

(iii) What is the maximum speed of the mass?

10. Which of the following function of time represent, (a) simple harmonic (b) periodic but not SHM and (c) non periodic ?

(i) Sinωt- Cosωt (ii) sin3ωt (iii) 3 cos ( π2−2ωt )(iv)exp (−ω2t 2)

(5 Marks Questions)

1. (a) A light wave is reflected from a mirror. The incident & reflected wave superimpose to form

stationary waves. But no nodes & antinodes are seen, why?

(b) A standing wave is represented by y=2ASinKxCoswt.If one of the component wave is

y1=ASin (ωt−Kx ) , what is the equation of the second component wave?

2. Discuss Newton’s formula for velocity of sound in air. What correction was made to it by Laplace and

why?

3. (a) What are beats? Prove that the number of beats per second is equal to the difference between

the frequencies of the two superimposing wave.

(b) Draw fundamental nodes of vibration of stationary wave in (i) closed pipe, (ii) in an open pipe.

4. Discuss the formation of harmonics in a stretched string. Show that in case of a stretched string the

first four harmonics are in the ratio 1:2:3:4.

5. Explain Doppler’s effect of sound. Derive an expression for the apparent frequency where the source

and observer are moving in the same direction with velocity Vs and Vo respectively, with source

following the observer.

6. For a travelling harmonic wave, y=2cos (10 t−0.008 x+0.35) where x & y are in cm and t in

second. What is the phase difference between oscillatory motions at two points separated by a distance

of (i) 4cm (ii) 0.5m (iii)λ2

(iv ) 3 λ4

?

7. (i) A steel rod 100 cm long is clamped at its middle. The fundamental frequency of longitudinal

vibrations of the rod is given to be 2.53 kHz. What is the speed of sound in steel?

(ii) A pipe 20 cm long is closed at one end. Which harmonic mode of the pipe is resonantly exited

by a 430 Hz source? Will this same source be in resonance with the pipe if both ends are open?

(Speed of sound = 340 m/s).

8. A train stands at a platform blowing a whistle of frequency 400 Hz in still air.

(i) What is the frequency of the whistle heard by a man running

(a)Towards the engine 10 m/s.

(b) Away from the engine at 10 m/s?

(ii) What is the speed of sound in each case?

(iii) What is the wavelength of sound received by the running man in each case?

Take speed of sound in still air = 340 m/s.

9. What is a spring factor? Derive the expression for resultant spring constant when two springs having

constants k1 and k2are connected in (i) parallel and (ii) in series.

10. Show that for a particle in linear S.H.M., the average kinetic energy over a period of oscillation is

equal to the average potential energy over the same period. At what distance from the mean

position is the kinetic energy in simple harmonic oscillator equal potential energy?

VALUE BASED QUESTIONS

1. Kanha visited his village during the holidays. One day he went for a morning walk. He saw a person trying to push a cart, but was not in a position to do so because of the muddy field. Kanha asked him for his help. He spread some pieces of stones along with the person, below the wheel cart. The wheel of the cart came out of the mud with his effort.

(i) What values were shown by Kanha?

(ii) What techniques were used by Kanha?

(iii) Name one advantage and one disadvantage of the physical quantity involved in second question in our day to day life.

2. One day Ram visited a nearby book shop along with his father to purchase some fiction. His father opened the book and started to read the preface of the book, in the meanwhile Ram observed that his father was unable to read the book properly. He requested his father to visit the nearby eye clinic and

get checked his eyesight .Next day Ram along with his father visited the eye clinic, where doctor advised him to put on the spectacles of power 2.5D.

(i) What values were executed by Ram?

(ii) From what defect the father of Ram was suffering.

(iii)Find the focal length and nature of the lens used.

3. Mr. David started ice skating recently under the guidance of Mr. Franklin. On the very first day Mr. David held the dumbles in his hands and started spinning on an ice track. Suddenly he fell down and got injured, Mr. Franklin quickly rushed toward him and carried him to a nearby hospital for the further treatment.

(i)What values were shown by Mr. Franklin. (ii) Why Mr. David fell down.

(iii) Name the principle behind the spinning of an ice skater.

4. Pinki along with grand father went to a nearby park for morning walk on a Sunday morning. There she saw a swing and requested her grandfather to swing herself. Her grandfather was pushing the swing and after some time he got tired and set down in the nearby bench. Pinki stands in the running swing due to which the speed and hence the amplitude of vibration of the swing increased by large amount, and Pinki started crying. After seeing this, a boy walking there rushed toward the swing and advised her to sit down in the swing. Now the swing started to swing with the lower speed and seeing this Pinki stopped crying.

(i) What were the values displayed by the boy.

(ii) What is the cause of the change in the speed of the swing?

(iii)Why the pendulum clock got slowed down on the mountain.

5. Three friends went to a hill station to celebrate the eve of New Year. The younger was making a phone call and get separated from his friends. He shouted loudly naming his friends .He observed that somebody was copying him and shouting the same words. He started crying, and got depressed and terrified. After some time his friends reached there , seeing his condition they sprinkled some water on his face and asked him about the mis happening occurred. His friend told him that the sound heard by him was nothing but an echo.

(i) What values were shown by his friends?

(ii) What do you mean by an echo?

(iii) How the echo is formed.

6. An old woman crossing the road was holding a money purse. She was not able to walk .A pick pocket snatches away her purse. A school student of class X having seen this incident tries to help that old lady. He informs the police Inspector who stands nearby. The Inspector collects the money purse from the pickpocket and hand it over to the old lady. (a)What values do you find in the school student? (b)Also the police inspector in a jeep is chasing the pickpocket on a straight

road. The jeep is going at its maximum speed ‘v’. The pickpocket rides on the motorcycle of a waiting friend when the jeep is at a distance ‘d’ away. and the motorcycle starts with a constant acceleration ‘a’. Show that the pickpocket will be caught if v≥√2ad.

7. Sita a student of class XII was suffering from malaria. The area is full of mosquitoes. She was not having mosquito net. Her friend Geeta has an extra net. She gave it to Sita. Also she took Gita to a Doctor, got her medicines. After a week Sita became normal (a) Comment upon the qualities of Sita. (b) The mosquito net over a 7 m X 4mbed is 3m high. The net has a hole at one corner of the bed through which a mosquito enters the net. It flies and sits at the diagonally opposite upper corner of the net(i) Find the magnitude of the displacement of the mosquito (ii)Taking the hole as the origin, the length of the bed as the X-axis, its width as the Y-axis and vertically up as the Z-axis, with the components of the displacement vector.

8. Krishna went for sightseeing to a nearby river along with his physics teacher. He noticed that the wind was blowing from the side and the sailboat still continued to move forward. He was surprised. He asked his physics teacher the explanation of this situation. The teacher having noticed his interest explained the concept through a small example. The physics of sailing is very interesting in that sailboats do not need the wind to push from behind in order to move. The wind can blow from the side and the sailboat can still move forward. The answer lies in the well-known principle of aerodynamic lift. Imagine you are a passenger in a car as it's moving along, and you place your right hand out the window. If you tilt your hand in the clockwise sense your hand will be pushed backwards and up. This is due to the force of the air which has a sideways component and upwards component (therefore your hand is pushed backwards and up). (a) What values could you find in Krishna? (b) Also explain what Magnus effect is.

9. Having found his mother suffering from fever Venkat took her to the doctor for treatment. While checking the status, the doctor used a thermometer to know the temperature of the body. He kept the thermometer in the mouth of the patient and noted the reading as 102◦ F. Doctor gave the necessary medicines. After coming home, Venkat asked his mother, who is a science teacher , why mercury is used in a thermometer when there are so many liquids. Then his mother explained the reason. (a) Comment upon the values of the mother. (b)A newly designed thermometer has its lower fixed point and upper fixed point marked at 5◦and 95◦ respectively. Compute the temperature on this scale corresponding to 50◦C

10. Having seen a big stone falling from the top of a tower Ravi pulled his friend Kiran away. The stone hit Ravi slightly and he got hurt. But he was saved from a major accident. (a)What made Ravi act in such a way. (b)From the top of a tower 100 m in height, a ball is dropped and at the same time another ball is projected vertically upwards from the ground with a velocity of 25 m/s. Find when and where the two balls meet. Take g = 9.8 m/sec2.