[edu.joshuatly.com] Pahang STPM Trial 2011 Physics (w ans).pdf

8/14/2019 [edu.joshuatly.com] Pahang STPM Trial 2011 Physics (w ans).pdf

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2

1 A certain physical quantity, R, is calculated using the formula: R = 4a2(b – c)

where a, b, and c are distances. What is the SI unit for R?

A cm B m C m2 D m

3

2 Which of the following is a scalar quantity?

A TorqueB Gravitational potential

C Angular momentum

D Acceleration

3 A car travels due east at 22 m s-1. It makes a turn due south and continues to travel

at 22 m s-1

. What is the change in velocity of the car?

A 22 m s-1

, due east

B 22 m s-1, due south

C 31 m s-1

, due south- west

D 31 m s-1, due south-east

4 An object of mass 6 kg is acted upon by a force F which varies with time t asshown in the diagram below. If the change of momentum of the object after time T is30 N s, what is the value of T?

A 3 s B 5 s C 6 s D 12 s

10

F/ N

t/sOT

http://edu.joshuatly.com



3

5 How much energy is dissipated in braking a 1000 kg car to a stop from an initialspeed of 20 m s-1?

A 20 000 JB 200 000 JC 400 000 J

D 800 000 J

6 A disc rotates horizontally with uniform angular velocity about an axis through itscentre. Which of the following graphs shows the correct relationship between the speed v

of a point on the disc and the distance r of the point from the centre of the disc?

7 If the angular velocity of a body performing circular motion is ω, the number of

revolutions per second is

A zero B 2πω C 2

D

2

8 The gravitational pull on a satellite on the surface of the Earth of radius R is F.

What is the gravitational pull on the satellite when it is at a height of 2R above theEarth?

A 1

2 F B

1

3 F C

1

9 F D 2F

O r

v

O r

v

O r

v

Or

v

A B

CD




4

9 When an ice skater spinning about a vertical axis spread his arms outwards awayfrom the axis of rotation, his speed of rotation decreases. Which is the most likely

reason?

A His moment of inertia decreases.B His centre of gravity is lowered.

C His moment of inertia increases.D The air resistance decreases.

10 Which one of the following statements is true concerning an object executingsimple harmonic motion?

A Its velocity is never zero.

B Its acceleration is never zero.C Its velocity and acceleration are simultaneously zero.

D Its velocity is zero when its acceleration is a maximum.

11 A particle performs simple harmonic motion. Which of the following graphs

represents the variation of potential energy with displacement?

O x+xo-xo

U

O x+xo-xo

U

AB

O x+xo

-xo

U

D-xo

+xoO

C

x

U




5

12 Resonance occurs in harmonic motion when

A the system is overdamped.

B the system is critically damped.C the energy in the system is a minimum.D the driving frequency is the same as the natural frequency of the system.

13 A wave of wavelength 1.0 cm is generated by a point source on a water surface.The phase difference between a point P and the source is 10.0 radians. The distance of the

point P from the source is

A 0.016 m

B 0.032 m

C 0.048 mD 0.064 m

14

The graph shows, at a particular instant, the variation of the displacement

of the particles in a transverse progressive water wave, of wavelength 4 cm, travellingfrom left to right. Which one of the following statements is not true?

A Particles at P and R are in a phase.

B The velocity of the particle at Q is a maximum.C The particle at S is moving downwards.

D The distance PS = 3 cm.




6

15 The intensity of a spherical wave 4.0 m from the source is 120 W m-2

. What is theintensity at a point 9.0 m away from the source?

A 11 W m-2 B 24 W m

-2

C 53 W m-2

D 270 W m-2

16 A car moving at 35 m s-1

approaches a stationary whistle that emits a 220 Hzsound. The speed of sound is 343 m s

-1. What is the frequency of sound heard by the

driver of the car?

A 198 HzB 220 Hz

C 242 Hz

D 340 Hz

17 Two wires X and Y of the same length and of the same elastic metal are each

stretched to the same tension. The diameter of wire X is half that of wire Y . The ratio

of the elastic potential energy stored in wire X to that stored in wire Y is

A 1 : 1. B 1 : 2. C 1 : 4. D 4 : 1.




7

18 The diagram below shows the graph of intermolecular force F against separation r between two molecules.

Which statement about the situation at point P is true?

A The potential energy is a maximum.

B The molecule is in a state of equilibrium.

C The force is a repulsive force.

D The force is an attractive force.

19 The r.m.s speed of nitrogen molecule at 300 K is c. What r.m.s speed if the

temperature of the gas is 1200 K

A c B 2c C 4c D 16 c

20 The diagram below shows the variation of pressure P with density ρ for an idealgas at 420 K and temperature T. What is the temperature T?

A 300 K B 323 K C 546 K D 840 K

F

P rO

420 K

2.00 2.60

ρ/ kg m-

P/Pa

O

T




8

21 A fixed mass of an ideal gas absorbs 750 J of heat and it expands at constant pressure of 1.0 x 105 Pa from a volume of 5.0 x 10-3 m3 to a volume of 7.5 x 10-3 m3. The

internal energy of the gas

A remains unchangedB increases by 250 J

C increases by 500 JD decreases by 250J

22 The molar heat capacity of an ideal gas at constant volume is less than at constant pressure because

A work is done against external pressure when the gas expands.

B the potential energy of the molecules increases when they are further apart.C work is done against intermolecular forces as the gas expands.

D the molecules acquire greater kinetic energy at constant pressure.

23 What is the work done on two mole of an ideal gas which is compressed

isothermally at 400 K from a volume of 10 cm3 to 30 cm3?

A 2.50 kJ B 3.65 kJ C 7.30 kJ D 8.50 kJ

24 Metal is a good thermal conductor because

A the average potential energy of the molecules is high.

B it has a lot of free electronsC its molecules are very close to one another.

D the size of the molecule is large.

25 A closed container contains water at 100oC. The container of total surface area of

0.5 m2 and uniform thickness of 4.0 cm has a thermal conductivity of 0.40 W m

-1 K

-1. If a

heater of power 300 W is needed to maintain the temperature of the water, the external

temperature is

A 80oC B 60

oC C 40

oC D 20

oC




9

26. The diagram below shows charges +q, +q and -q which are fixed at points X, Y and Z

of a circle respectively.

The resultant electric field at centre 0 of the circle is in the direction of

A OY B OZ C YO D ZO

27. A wire of length l and cross-sectional area A has a resistance R. If the resistivity of

the material of the wire is ρ, the electrical conductivity σ is

A l

AL

B RA

l

C l

R

D

LA

R




10

28. Two cylindrical resistors are each made from copper and aluminium. The cross-

sectional area and resistivity of aluminium are three times the cross-sectional area and

resistivity of copper. If the volumes of the two resistors are the same, what is the ratio of

the resistance of the aluminium resistor to the resistance of the copper resistor?

A 1:3 B 1:9 C 3:1 D 9:1

29. A cell of internal resistance 2.0 Ω is connected to a resistor of 8.0 Ω. The percentage

of power from the cell which is supplied to the resistor is

A 20% B 64% C 80% D 100%

30. A 5 μ F capacitor is charged until the potential difference is 12 V before it is

disconnected from the supply. The capacitor is then connected in parallel to an uncharged

10 μ F capacitor. The common potential difference of the two capacitors is

A 4.0 V B 6.0V C 9.0V D 12.0V

31 When the load decreases, the speed of rotation of an electric motor increases and

the current flowing through it decreases. This happens because

A the back e.m.f. increases

B the' frictional force decreases

C the resistance of the armature coil increases

D the inductance of the armature coil increases






12

34. The planes of vibration of the electric and magnetic fields in an electromagnetic waveare

A parallel to each other and parallel to the direction of the propagation of the wave

B perpendicular to each other and parallel to the direction of the propagation of the

wave

C parallel to each other and perpendicular to the direction of the propagation of thewave

D perpendicular to each other and perpendicular to the direction of the propagation

of the wave

35. Which of the following graphs shows the variation ofv

u , where u is the object

distance and v the image distance of a convex lens?

A B

C D




13

36. The image of an object which is formed by a convex mirror is always

A real and big C virtual and big

B real and small D virtual and small

37. Which statement is not true of the back e.m.f. of an electric motor?

A The back e.m.f. opposes the applied voltage.

B The back e.m.f. is caused by electromagnetic induction.

C The back e.m.f. helps to increase the magnitude of the current flowing through the

coil of the motor.

D The magnitude of the back e.m.f. increases if the speed of rotation of the coil of the

motor is increased.

38. An a.c. power supply with a constant r.m.s. voltage and variable frequency is

connected in series to a pure inductor. Which graph shows the variation of the r.m.s.

current I with the frequency f ?

A B

C D

I




14

39. The alternating voltage supplied to a 200 μF capacitor is given by V = 5 sin 300t

where V is in volts and t in seconds. The maximum current in the circuit is

A 0A B 0.21 A C 0.30A D 83 A

40. The diagram below shows a circuit of an inverting amplifier.

An input voltage of +2 V produces an output voltage of -8 V. Which statement about the

circuit is not true?

A The value ofi

f

R

R is 4.

B The voltage gain is - 4.

C When the input voltage is -1 V, the output voltage is +4 V.

D When the input voltage is 2 V, the potential at point P is 2 V,

41. Which statement is true of an electromagnetic spectrum?

A Radio waves are longitudinal waves.

B Only the visible spectrum can be plane polarised.

C Gamma rays have a higher frequency than infrared waves.

D X-rays travel at a higher speed than ultraviolet waves.




15

42. The diagram below shows monochromatic light of wavelength A which is illuminated

nearly normal onto a thin soap film of thickness t and refractive index n.

The optical path difference between the reflected rays from the upper and lower

surfaces of the soap film is

43. In the photoelectric effect, the energy of the photon is

used

A to release the electron from the lattice only

B as the kinetic energy of the electron only

C to release the electron from the lattice and as the kinetic energy of the electron

D by the electron to produce a new electron called photoelectron




16

44. If λ is the wavelength of a particle with momentum p, which graph has a gradient

equal to the Planck constant?

45.The diagram below shows some of the energy levels of an atom.

------------------------------------- E 4

------------------------------------ E 3

-------------------------------------E 2

------------------------------------- E 1

The maximum number of spectral lines produced by the transition of electrons from

these four energy levels is

A 3 B 4 C 5 D 6




17

46. The diagram below shows the X-ray spectra I and 11 produced by an X-ray tube when

it is operated at two different voltages.

Which statement explains why the minimum wavelength of spectrum II is longer thanthat of spectrum 1?

A A lower voltage is used to produce spectrum II.

B A higher voltage is used to produce spectrum II.

C A lighter element is used as the target material to produce spectrum II.

D A heavier element is used as the target material to produce spectrum II.




18

47. Which statement is

nottrue of stimulated emission?

A Photons emitted by stimulated emission are in phase.

B Photons produced by stimulated emission are of different frequencies.

C Radiation produced by stimulated emission in a laser is monochromatic.

D Radiation produced by stimulated emission in a laser has high intensity.

48. The nucleus of iron 56

26Fe is more stable than the nucleus of bismuth 209

83Bi. Which of the

following is true of the more stable nucleus?

A Higher binding energy per nucleon

B Lower ratio of proton to neutron

C Higher mass per nucleon

D Lower binding energy per nucleon

49. Which statement is not true of stimulated emission in laser production?

A The photon emitted is in phase with the incoming photon.

B A photon is emitted when an incoming photon is absorbed.

C One incoming photon will cause two photons to be emitted.

D The photon emitted moves in the same direction as the incoming photon.

50. A high energy particle which is emitted when a beryllium foil is bombarded by an

alpha-particle is a

A proton B neutron C beta-particle D gamma-ray photon




2

SectionA [ 40 marks ]

Answer all questions in this section

1 The diagram below shows a projectile launched at angle with the horizontal.

Find the angle of projection at which the horizontal range and the maximum height of a

projectile are equal.

[5 marks]

y

x

Range

Maximum Height




3

2 A string of length, l fixed at one end and a bob of mass, m is attached on another end. A

conical pendulum is formed when the bob moves in a horizontal circle as shown in the diagram

below.

(a) Show that the frequency of oscillation, f is given by

1

2 cos f

l

where g is the acceleration due to gravity and is the angle between the string and the vertical.

[5 marks]

l

m

O




4

3 A wire has mass 5.3 g and length 2.50 m. A force of 50 N extends it by 2.3 mm.

If the density of wire is 2.7 x 103 kg m-3, determine:

(a) the Young’s modulus of the wire.

[3 marks]

(b) the strain energy per unit volume stored in the stretched wire.

[2 marks]




5

4 A gas tank contains 1 mol of gas at pressure 1.0 x 105 Pa. Assuming that the gas behaves

as an ideal gas,

(a) calculate its volume at 170C.

[2 marks]

(b) find the ratio of the volume of a molecule of gas to the volume of 1 mol of gas, if

the diameter of a molecule is 2.5 x 10-10

m.

[3 marks]




6

5. A dry cell of e.m.f. V and negligible internal resistance is connected to three resistances of

resistance R1, R2 and R3 as shown in the diagram below.

Currents I , I 1, I 2 and I 3 flows through the dry cell and resistors R1, R2 and R3 respectively.When the same dry cell is connected to a resistor R , the same current I flows through the dry cell

as shown in diagram (b).

a) State the relationship between I , I 1, I 2 and I 3.

[1 mark ]

b) Hence, show that

321

1111

R R R R

[1 mark ]

c) You are given four identical resistors of resistance 3 each. Draw a diagram to show

how you would connect these four resistors to obtain an effective resistance of 4 .

[1 mark ]

I V

I1

I2

I3

R 1

R 2

R 3

Diagram (a)

I V

I3 R

Diagram (b)




7

X Y3 3 3 3

d) The four resistors above in (c) are connected as shown below. Calculate the effective

resistance between X and Y.

[2 marks]




8

6.

A, a very strong bar magnet is dropped from a height H in air as shown in diagram

(a) above. The time taken for it to reach the ground is T .

It is then dropped from the same height H into a long hollow cylinder made from a good

conductor as shown in the diagram (b) above.

a) Compare the time taken in both instances, T and t . [1 mark ]

b) Use appropriate physics concepts and principles to explain your description.[4 marks]

A

H

Diagram (a)Diagram (b)

A

H




9

7. The diagram below shows an operational amplifier circuit.

(a) Name the operational amplifier circuits.

(State whether it is an open-loop circuit, inverting amplifier or non-inverting amplifier)

[1 mark ]

(b) State the use of the operational amplifier circuit.[1 mark ]

(c) When an input voltage V i = 5 sin 2t is applied, calculate the output voltage Vo.

[3 marks]

-9V

+9V

2F

5 M

V0

Vi

+

-




10

8. X-rays can be diffracted by a crystalline solid.

(a) What does this fact suggests about

(i) X-rays

[1 mark ]

(ii) the crystalline solid[1 mark ]

(b) X-rays with a wavelength of of 1.5 x 10

-10

m is directed towards a crystalline solid andstrong X-rays of the third order reflection are detected when the glancing angle is 600.

Calculate the separation between the atomic planes of the crystalline solid.

[3 marks]




11

Section B [ 60 marks]

Answer any four questions in this section.

9. (a) Define work done on a body by a force [2 marks]

(b) Using the work – energy theorem show that work done by a constant force F

pushing a block of mass m on a smooth horizontal surface is equal to the change

in the kinetic energy of the block. [4 marks]

(c) The diagram below shows a car of mass 1200 kg going up a slope with a constant

speed of 20 m s

-1

. The total amount of resistance to the car is 900 N and theangle of inclination of the slope is 20

0,

(i) Calculate the component of the weight along the slope. [3 marks]

(ii) If the car is to move up the slope , what should be the minimum force

exerted by the engine of the car? [2 marks]

(iii) Calculate the power developed by the engine [3 marks]

(d) If the power output of the car’s engine is increased, describe the change in the motion

of the car. [1 mark ]

10. (a) State Newton’s Law of Gravitation [2 marks]

(b) An object of mass 1.0 kg is 3.8 x 108 m from the centre of the earth.

Calculate the gravitational force exerted by the earth on the object.

[Mass of Earth= 6.0 x 1024 kg] [2 marks]

(c) Assuming that the moon travels at a constant speed around the earth in a circle of

radius 3.8 x 108 m , calculate

(i) the acceleration of the moon. [3 marks]

(ii) the period of the moon’s rotation [3 marks]

(d) (i) State the units for gravitational field strength [1 mark ]

200




12

(ii) Why is it incorrect to call g (=9.8 m s-2

) ‘ gravity ‘? [2

marks]

11. (a) Define simple harmonic motion. [2 marks]

(b) The diagram shows a light helical spring with a spring constant k. The spring is

Allowed to hang vertically with a mass M attached to its free end. The mass is

displaced vertically and then released.

(i) The motion may be considered to be simple harmonic if two conditions are

satisfied. State one condition. [1 mark ]

(ii) Show that the frequency of the motion , f is given by

1

2

k f

M [3 marks]

(c) The rise and fall of the water level in some harbours is simple harmonic.

In one harbour ,the depth h of water is given by the equation

h = 5.0 + 3.0 sin (2

45600

t )

Calculate

(i) the two values of t at which the water reaches 5.0 m [3 marks]

(ii) the length of time for each tide during which the water reaches 7.0 m or more.

[4 marks]

M

spring




13

12 (a) In a Young’s double -slit experiment ,the separation of the slit is 0.5 mm and

the distance between the slits and the screen is 200 cm. When red light is used,

the distance between the centre of the interference pattern and the first bright

fringe is 0.15 cm.

(i) Find the wavelength of the red light used. [ 3 marks ]

(ii) Find the distance between the center of the interference pattern and the third

dark fringe. [ 2 marks ]

(iii) If the space between the slits and the screen is filled with a liquid of refractive

index 1.20, explain what will happen to the interference pattern on the screen.[ 2 marks ]

(b) A beam of parallel monochromatic light falls on a single slit 0.1 mm wide.

A convex lens of focal length of 50 cm is placed in front of the slit to focus the

light that passes through the slit onto a white screen . If the width of the centralmaximum of the diffraction pattern produced on the screen is 3.5 mm,

determine the wavelength of the monochromatic light used. [ 4 marks ]

(c) Light from a hydrogen flame is incident normally onto a diffracting gratingwhich has 3000 lines per cm. If the wavelength of the line α and δ for the

hydrogen atom are 655 nm and 410 nm respectively, determine the angular

separation between the two lines in the second order of the spectrum produced

by the diffracting grating [ 4 marks ]




14

13 (a) (i) What do you understand by photon ? [1 mark ]

(ii) If E is the energy of a photon in J and λ is the wavelength of the photon in

nm , show that Eλ = 1.99 x 10-16

. [ 2 marks ]

(b) (i) Explain what is meant by photoelectric effect . [1 mark]

(ii) Write down Einstein’s equation for this phenomenon and explain the terms

work function and threshold frequency . [ 3 marks ]

(c) A zinc surface is radiated with ultraviolet light of wavelength 280 nm . By

assuming that the photoelectric work function of zinc is 3.66 eV, calculate the

maximum energy photoelectrons emitted .If the same surface is radiated by an

ultraviolet light of wavelength 200 nm, state whether the photoelectrons emitted

have a lower or higher maximum energy. Give reasons for your answer.[ 5 marks ]

(d) If this page of this question paper is illuminated by 100 W m-2 of light of

wavelength 625 nm,calculate

(i) the power received by an area of 1.0 cm2 . [ 1 mark ]

(ii) the number of photons striking each square cm per second . [ 2 marks ]




15

14 (a) (i) In the nucleus of an atom, there are electric repulsive forces between the

protons in the nucleus, and nuclear forces that bind the nucleons together.

Compare these forces from their range of action , their strength, and their

dependence, if any , on the charges. [ 3 marks ]

(ii) The radius of the nucleus of an atom can be assumed to be given by the

equation

R = R 0 A1/3

where R 0 is a constant, and A is the mass number of the nucleus.

Show that the nucleus of ALL atoms can be assumed to possess the samedensity ,stating any assumptions needed . [ 3 marks ]

(b) A research nuclear reactor of 30 % efficiency can produce a maximum power of

5.0 MW.The nuclear fuel is 23592

U atoms, and the nuclear reaction that occurs in

the reactor can be assumed to be represented by the equation

235 1 148 85 1

92 0 57 35 03U n La Br n

Calculate

(i) the energy released by each of the 23592

U atom which undergoes the fission.

[ 2 marks ]

(ii) the number of 235

92U atoms used by the reactor in a period of 10 hours if

the reactor is operating at maximum power . [ 2 marks ]

(iii) the minimum mass of235

92U required if the reactor is set to operate atmaximum power for 180 days a year for a period of 10 years. [ 3 marks ]

[ Mass of 235

92U = 235.0439 u , mass of 148

57 La = 147.9314 u ,

mass of 85

35 Br = 84.9156 u, mass of 1

0 n = 1.0087 u ]

(c) In a process of complete annihilation, the fusion of an electron and a positron

causes the two particles to perish, but are replaced by the production of two

γ-ray photons only. By using the principle of conservation of mass-energy,

calculate the energy of each γ-ray photon produced. [ 2 marks ]




Marking Scheme Physics Paper 1

1 D 21 C 41 C A 11

2 B 22 A 42 D B 14

3 C 23 C 43 C C 15

4 C 24 B 44 B D 10

5 B 25 C 45 D JUM 50

6 A 26 B 46 A

7 C 27 B 47 B

8 C 28 A 48 A9 C 29 C 49 B

10 D 30 A 50 B

11 A 31 A

12 D 32 D

13 A 33 B

14 A 34 D

15 B 35 A

16 C 36 D

17 D 37 C

18 B 38 C

19 B 39 C

20 C 40 D




1.

If the range = R, and maximum height = H

Vertical motion

asuv 222

gH u 2sin0 22

g

u H

2

sin22 ………………………1

Horizontal motion

at uv

gt u sin0

g

ut

sin

t u R 2cos …………………….1 (time = 2t)

g

uu R

sin2cos

g

u R

cossin2 2

………………..1

H = R …………………………….1

g

u

2

sin22

g

u cossin2 2

Tan = 4

= 75.960 or 750 58’ .................1

Alternative answer :

Horizontal range = Maximum height …………………………….1

2 2 2sin 2 sin

2

u u

g g

……………………………..(3)

2 sin2 = sin2

2 ( 2sin cos) = sin2

4 sin cos - sin2 = 0

sin (4cos - sin) = 0




sin = 0 or 4cos - sin = 0

= 00 , 1800 tan = 4

(not define) = 75.960 or 750 58’……….(1)

2 T sin = mr 2 …………………………(1)

T sin = m (l sin ) (2 f )2 ………….(1)

T = 42 f 2 ml ………………….(1)

T cos = mg …………………………(1)

(42 f

2 ml ) cos = mg ………………….(1)

1

2 cos

g f

l

3(a) strain

stress E ...................................(1)

FL E

Ax

m

AL or

m A

L ...............(1)

2 F L E

mx

3 2

3 3

(50)(2.7x10 )(2.50)

(5.3x10 )(2.3x10 ) E

E = 6.92 x 1010 Pa ……………………….(1)




(b) Strain energy per unit volume

=1

x stress x strain2

...........................(1)

=1

( )( )2

F x

A L,

m A

L

=1

( )2

F x

m

=3 3

3

(50)(2.7x10 )(2.3x10 )

(2)(5.3x10 )

= 2.93 x 104 J m-3 ……………………(1)

4(a) pV = nRT .................................................(1)

(1.0 x 105)V = (1)(8.31)(290)

V = 0.0241 m3 …………………….(1)

(b) Ratio of the volume of a molecule to the volume of 1 mol of gas

=

34( )

3 2d

V

……………………..(1) for volume of molecule

=

1034 2.5 10

( )3 2

0.0241

x

………………(1)

= 3.39 x 10-28 ……………………..(1)




5(a)

I = I1 + I2 + I3 …………………………(1)I = I1 + I2 + I3

(b)

321 R

V

R

V

R

V

R

V ……………………………(1)

321

1111

R R R R

(c)

………….(1)(d)

………(1)

31

31

31

'1

R

R’= 1

R = 1 + 3 = 4




6(a)

t > T ………………………………………….(1)

(b)

In diagram (a)The magnet will drop under the influence of gravity ignoring air resistance.

In diagram (b)When the magnet falls, the conductor experience a change in magnetic field.According to Faraday’s Law, a current will be induced in the conductor

………………………………..(1)

According to Lenz’s Law the direction of current induced in the conductor will produce amagnetic field that causes a force that acts upwards on the magnet.

………………………………….(1)

The nett force acting downwards will be smaller than in figure (a) ……….(1)

According to Newton’s second law of motionIts acceleration downwards will also be smaller. …………………..(1)

Thus the time taken will be longer.

7.(a)

Inverting amplifier…………………………(1)

(b)Integrator………………………………….(1)

(c)

dt V CR

V io 1 …………………………(1)

=

dt t 2sin5105102

166

= dt t 2sin5.0

=

2

2cos5.0

t ……………..(1)

2

2cos t

= 0.25cos2t or

4

2cos t ……………….(1)




8(a)(i)If X-rays are diffracted, it shows that X-rays are waves since diffraction is a wave property. ……………………………..(1)

(ii)

The atoms in the crystalline solid are arranged in parallel planes with the atomic planeseparation of the same order of magnitude as the wavelength of X-rays…………………………….(1)

(b)2d sin = n

0

10

60sin2

105.13

d ………………(1)

=2.60 x 10-10 m ………………(1)




9. (a) W = F.s …………………………………..(1)

F is force and s is displacement in the direction of the force. ……………(1)

(b) The initial velocity of the block = u

After being displaced through a distance s , final velocity of the block = v

Work done by the force = Fs

= mas [ F = ma ] …..(1)

[v2 = u

2 + 2as] ………………………………………………………………(1)

as = ½ ( v2 – u2)

Word done = ½ m ( v2 – u2 ) …………………….(1)

= ½ mv2 – ½ mu2 …………………….(1)= increase in kinetic energy

(c) (i) F = mgsinθ ……………………………………………………….(1)

= 1200 x 9.81 x 0.3420 ………………………………………...(1)

= 4026 N ……………………………………………………….(1)

(ii) Force = 4026 + 900 ………………………………………………(1)

= 4926 N ………………………………………………(1)

(iii) Power = force x velocity …………………………………………...(1)= 4926 x 20 ………………………………………………...(1)

= 98520 W ………………………………………………...(1)

(d) The car will begin to accelerate up the slope. ……………………………(1)






11. (a) A body is in simple harmonic motion if its acceleration is directly proportional to its

displacement x from a fixed point and is constantly directed towards its fixed point.

Acceleration = - ω2 x ω

2 = constant ………(2)

or

Simple harmonic motion is a periodic oscillation.

(i) The acceleration is always directed to the the equilibrium position. ……….(1)

(ii) The acceleration is directly proportional to the displacement ……………(1)

(b) (i) The maximum displacement x should not exceed the Hooke’s limit i.e. x should

not exceed Mg / k / The system is conservative ,i.e there is no friction or only

light damping ……………………………………………………………..(1)

(ii) At equilibrium T = Mg = ke

When the mass is displaced x downwards where x < e

k(e+x) – Mg = - Ma ………………………………………………….(1)

ke + kx – Mg = -Ma

kx = - Ma

acceleration of a spring on mass is a = - kx / M ……………………………………(1)

since a / x = - ω2 therefore ω2 = k / M

but ω= 2πf …………………………………………………………...(1)

so f = 1/2π √ k / M

(c) (i) When h = 5.0 ,

sin (2πt / 45600) = 0 or sin (2πt / 45600) = π or 2π ............(1)

correct substituitions …………………………………………………..(1)

t = 22800 s or t = 45600 s ……………………..(1)

(ii) when h = 7.0 m

h = 5.0 + 3.0 sin (2πt / 45600)

7.0 = 5.0 + 3.0 sin (2πt / 45600)

sin (2πt / 45600) = 2/3 = 0.6667 ................................................(1)

(2πt 1/ 45600) = 0.7297 or (2πt 2 / 45600) = π – 0.7297 = 2.4119 ............(2)t1 = 5296 s or t2 = 17504 s …………….(1)




Hence the length of time during which the depth of water reaches more tha 7.0 m

= (t2 – t1) s

= (17504 - 5296) s ……………………..(1)

= 12208 s ………………………………….(1)

( from the sine curve at h = 7.0 m , two values of t can be found )




12 (a) (i)

(ii)

(iii)

λ = x a/ D

= (0.15 X 10-2) ( 0.5 x 10-3) / 2.00

= 3.75 x 10-7 m

x = ( 3 – ½ ) λD / a

= (2.5 x 3.75 x10-7 x 2.0 ) / 0.5 x10-3 m= 3.75 x 10-3 m

In liquid ,the wavelength of red light becomes shorter.The fringes become closer to each other

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(b)sinθ = θ = λ/a

θ = d /2 /f = d / 2f

d / 2f = λ/a , λ = da/2f = (3.5 x 10-3 )x (0.1 x 10-3)/ 2 x 0.5

= 3.5 x 10-7 m

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(c) d = 1 x10-2 / 3000 = 3.33 x 10-6 m

d sinθ n = nλ

for α line, d sinθ2 = 2λ

sinθ2 = 2 ( 655 x10-9) / 3.33 x10-6

θ2 = 23o 10’

for δ line, sin θ2’ =2 ( 410 x 10-9

) / 3.33 x10-6

θ2’ = 14o 15’

θ2 - θ2’ = 8o 55’

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13 (a) (i)

(ii)

Energy in electromagnetic radiations consists of discrete packets called

photons its energy is E = hυ where h is Planck’s constant

and υ is the frequency of the wave

E = h υ = hc/ λ,

E λ x 10-9 = hc

E λ = 6.63 x 10-34 x 3x108 x 109

= 1.99 x 10-16

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(b) (i)

(ii)

Emission of electrons from a metal surface when electromagnetic radiationof sufficient frequency falls on it .

hυ = W + ( ½ me v2 )max

Work functionW = h υo , minimum energy required by a free electron in the metal

surface to escape from the surface

Threshold frequency υo , is the minimum frequency of the electromagneticradiation below which no electrons will be emitted from the metal surface

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(c) hυ = W + ( ½ me v2 )max

( ½ me v2 )max = hc/λ – W

= 6.63 x 10-34 x 3 x108/ 280 x10-9 - 3.66 x 1.6 x 10-19

= 1.247 x 10-19 J or 0.7797 eV

With 200 nm , ( ½ me v2 )max will be higher because the energy of the

photons is higher

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(d) I = 100 W m-2 Power = IA = 100W x 1.0 x 10-4 = 0.01 W

n hυ /t = 0.01n/t = 0.01 x λ / hc = 0.01 x 625 x 10-9 / 6.63 x10-34 x 3x 108

= 3.142 x1016

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14 (a) (i)

(ii)

Strong nuclear force is short range compared to electrostatic repulsive forcewhich has larger range.

Strong nuclear force is much stronger than electrostatic repulsive forceStrong nuclear force does not depend on charges but electrostatic forcedepends on charges

m p = mn = m ( assumption )

mass of nucleus = Am

volume = 4/3 π r 3 = 4/3 π ( R o A1/3 ) = 4/3 π A R o3

density = Am / 4/3 π A R o3 = 3m / 4π R o

3

= constant

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(b) (i)

(ii)

(iii)

(c)

∆ m = ( 235.0439 + 1.0087) – ( 147.9314 + 84.9156 + 3 X 1.0087 )

= 0.1795 u∆ E = ∆ m c2 = (0.1795 x 1.66 x 10-27 ) X ( 3x 108 )2

= 2.682 x 10-11 J

5 x 106 x 10 x 60x60 = 1.8 x 1011 J

With 30 % efficiency , actual energy produced is 1.8 x 1011 / 0.3

= 6.0 x 1011 J

No. of atoms used = 6 x 1011 / 2.682 x 10-11 = 2.237 x 1022

No. of atoms used in 10 years = 10 x 180 x24 x 2.237 x1022/ 10

= 9.664 x 1025

No. of moles = 9.664 x 1025 / 6.02 x1023 = 160.53

Mass of 235 U used = 160.53 x 235.0439 = 37.73 kg

E = mc2 = 2 x me c2 = 2 x 9.11 x 10-31 x 9 x 1016 J

Energy of each γ photon = 9.11 x 10-31 x 9 x 1016 J= 8.20 x 10-14 J

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Documents

[edu.joshuatly.com] Pahang STPM Trial 2011 Physics (w ans).pdf