Tunku Abdul Rahman University College Exam Paper

KOLEJ UNIVERSITI TUNKU ABDUL RAHMAN

CENTRE FOR PRE-UNIVERSITY STUDIES

ACADEMIC YEAR 2014/2015

SEPTEMBER EXAMINATION

FPPH1024 GENERAL AND THERMAL PHYSICS

JANUARY 2014 (2 HOURS)

FOUNDATION IN SCIENCE

Instructions to candidates:

1. This question paper consists of TWO sections.

2. Write in dark blue or black pen.

3. Do not use staples, paper clips, highlighters, glue or correction fluid.

4. Answer ALL questions in the answer booklet(s) provided and follow all the instructions stated on

the answer booklet(s).

SECTION A: MULTIPLE CHOICE QUESTIONS (30 MARKS)This section consists of FIFTEEN (15) questions.Answer ALL questions.

SECTION B: STRUCTURED QUESTIONS (70 MARKS)This section consists of EIGHT (8) questions.Answer ALL questions.

This question paper consists of 23 questions on 12 printed pages.

2FPPH 1024 GENERAL AND THERMAL PHYSICS

Data and Formulae

speed of light in free space, c=3.00×108ms−1

permeability of free space, μ0=4 π ×10−7 H m-1

permittivity of free space, ε 0=8.85×10−12 F m-1

elementary charge, e=1.60×10−19C

the Planck constant, h=6.63×10−34 Js

capacitors in series, 1C

= 1C1

+ 1C2

+…

capacitors in parallel, C=C1+C2+…

resistors in series, R=R1+R2+…

resistors in parallel, 1R

= 1R1

+ 1R2

+…

alternating current/voltage, X=X0 sinωt

simple harmonic motion, a=−ω2 x



SECTION A: MULTIPLE CHOICE QUESTIONS (30 MARKS)

Q1. A 2000μF capacitor is charged to a potential difference of 9.0V.

Calculate the energy stored by the capacitor.

A. 9.1×10−2J

B. 4.05×10−2J

C. 8.1×10−2J

D. 1.8×10−1J

Q2. The diagram below shows a circuit consisting of a battery and four capacitors. Calculate the total capacitance in the circuit.

A. 150μFB. 183μFC. 200μ FD. 700 μF

Q3. A current of 0.20 A flows through a lamp and the potential drop across the lamp is 3.0 V, what is the resistance of that lamp?A. 0.6 ΩB. 1.2 ΩC. 1.5 ΩD. 3.0 Ω

Q4. When will 5 C of charge go through a point in an electrical circuit?A. when a power of 5 W is used for 1 s.B. when 5 A of current moves through a potential difference of 5 V.C. when 5 A of current moves through a potential difference of 1 V.D. when the current is 0.5 A for 10 s.



Q5. The diagram below shows a current-carrying circuit consists of three resistors. The ammeter has negligible internal resistance.

What is the reading of the ammeter?

A . 0.7 AB . 1.3 A C. 2.0 A D . 2.3 A

Q6. In the circuit below, R1 and R2 are unknown resistors, XY is a length l of uniform resistance wire. J

is a sliding contact that joins the junctions of R1 and R2 to points on XY through an ammeter.

A point is found on XY at which the reading of the ammeter is zero. This point is at a distance x from X.

What is the value of the ratio V 1/V 2?

A. x

l−xB. xl

C. xl

D.

l2

(x¿¿2+(1−x )2)+x (R1)

l(R¿¿1+R2)¿¿



Q7. A power cable A carries current I and has resistance R. A second power cable B has resistance 2 R

and carries current 12I . What is the ratio

power dissipated∈Apower dissipated∈B

?

A. 41

B. 12

C. 2

D. 14

Q8. The figure below shows a a wire carrying a current I which is out of the page and a uniform magnetic field B directed to the left.

The magnetic force acting on the wire is directed

A. downward

B. to the left

C. upwards

D. to the right

Q9. How much current must flow through a wire in order to produce a 1.0×10−3 T magnetic field at a

distance of 0.05 m from the wire?A. 200 AB. 250 AC. 267 AD. 300 A

Q10. An ideal solenoid of 0.75 m long has 1000 loops wound on it. Compute the magnetic field, B, in its interior when a current of 0.45 A flows through it.

A. 5.5×10−4TB. 6.5×10−4T



C. 7.5×10−4TD. 8.5×10−4T

Q11. A positive charged particle is accelerated from rest through a potential difference. After that, it enters a uniform magnetic field oriented perpendicular to its path. The magnetic field causes the particle to move in a circular arc of radius R. If the accelerating potential is doubled, the radius of the arc will now beA. 2RB. √2RC. 4 RD. R

Q12. A train is moving towards north with a speed of 15 ms-1. If the downward vertical component of the

Earth’s magnetic field is 5.4×10−5T, calculate the magnitude of the e.m.f. induced in the train

axle of 1.5 m long.

A. 1.2×10−3V

B. 2.6×10−3V

C. 2.9×10−3V

D. 3.5×10−3V

Q13. Lenz’s law is the consequence of which physical law?A. Newton’s first lawB. Law of conservation of linear momentumC. Law of conservation of chargeD. Law of conservation of energy

Q14. The value of the voltage of an alternating current is represented by the equation V=5 sin (50πt ). This a.c. mains is connected to the primary coil of a transformer, which contains 10 turns. The r.m.s. output of the transformer is 6.0V.Determine the number of turns on the secondary coil.A. 17B. 18C. 20D. 21

Q15. A 100 Ω resistor is connected to an a.c. supply. The waveform of the voltage across the resistor is shown in the figure below.



Determine the mean power dissipated in the resistor.A. 0.45 WB. 0.82 WC. 8.0 WD. 16 W



SECTION B : STRUCTURED QUESTIONS (70 MARKS)

Q1. a) For the circuit below (figure 1), determine the total capacitance of the circuit. (3 marks)

b) Calculate the potential difference across the capacitor A in figure 1. (2 marks)

c) Calculate the total energy stored by the capacitors. (2 marks)

[Total:7 marks]

Q2. a) A 6 V, 32 W heater is operated for 1 hour. Calculate (i) the energy dissipated by the heater. (2 marks)(ii) the current in the heater. (2 marks)

(b)

b) State the relation between force and momentum. (2 marks)

c) A car of mass 800 kg makes a head-on collision with a stationary lorry of mass 1200 kg. The car and the lorry are then moving together with a common speed, v. Before the collision, the car was travelling at a velocity of 25 m s−1.

i) Calculate the combined speed of the tangled vehicles immediately after the collision. (2 marks)

ii) Calculate the initial kinetic energy of the car and the final kinetic energy of the tangled car and lorry immediately after the collision. (2 marks)

iii) Use your answer to (ii) to determine whether the collision is elastic or inelastic. Explain your reason. (2 marks)

[Total : 11 marks]


Figure 1


Q3. a) Determine the SI base units of resistivity (3 mark)

b) A variable resistor R and a metal wire with non-negligible resistance as shown in figure 3 are connected to a cell of e.m.f. 3.0 V. The wire is 0.50 m long and has an area of cross-section of 1.5×10−7m2. The resistance of the wire is 1.5 Ω.

figure 3

i) Determine the resistivity of the metal wire. (2 marks)

ii) Calculate the power dissipated in the wire when the potential difference across the wire is 1.5 V (2 marks)

iii) The resistance of R may be varied between 0 and 1000Ω. Calculate the maximum potential difference and minimum potential difference possible in the wire. (2 marks)

iv) The resistance of R is now set to be 500 Ω. Calculate the potential difference across the wire and the power dissipated in the wire. (3 marks)

[Total: 12 marks]



The container has vertical sides and a base of area, A.

i) State, in terms of A ,h and ρ, the mass of liquid in the container. (1 mark)

ii) Derive an expression for the pressure P exerted by the liquid at the base of the container. (2 marks)

c) The density of water is 1000 kg m−3 and the density of alcohol is 850 kg m−3.

i) Calculate the ratio of the mass of 2.0m3 of water to the mass of 3.0 m3 of alcohol. (2 marks)

ii) This 3.0 m3 of alcohol is then mixed with 2.0m3 of water to form a mixture. Assuming that the total volume remains unchanged, calculate the density of the mixture.

(2 marks)

[Total : 8 marks]

Q4. a) Define the following terms:

i) principle of moments, (2 marks)

ii) torque of couple. (2 marks)

b) The diagram shows a straight, horizontal and uniform swinging spring board of length 3.0 m and weight 70 N which is hinged at point B. A box of weight 1650 N is located at the point A.



Figure 2

Determine the weight of the person who is standing at point C. (3 marks)

[Total: 7 marks]

Q5. A fibre made of glass is loaded until it breaks. It has a length of 0.20 m and cross-sectional area 6.9×10−7 m2. The variation with load F of the extension x of the fibre is shown in Figure 3.

Q5. (Continued)

a) State with reason whether the glass is ductile, brittle or polymeric. (2 marks)

b) Use Figure 3 to determine, for this sample of glass,

i ) the ultimate tensile stress (where the glass is at its breaking point), (2 marks)


Figure 3


ii) the Young modulus, (3 marks)

iii) the maximum strain energy stored in the fibre before it breaks. (2 marks)

[Total : 9 marks]

Q6 a) State what it meant by the angular speed ω. (2 marks)

b) A stone of weight 3.0 N is glued to one end P of a rigid rod OP, as shown in Figure 4.

The rod is rotated about the end O so that the stone moves in a vertical circle of radius 85 cm. The angular speed ω of the rod and stone is gradually increased from zero until the glue snaps and the stone flies away. The glue holding the stone snaps when the tension in it exceeds 20 N.For the position of the stone at which the glue snaps,

i) mark with the letter X the position of the stone on the dotted circle of Figure 4, (1 mark)

ii) calculate the angular speed ω of the stone. (5 marks)

[Total: 8 marks]


mg=3N

Figure 4


Q7. A planet X is considered to be a uniform sphere with its mass M concentrated at the centre. A satellite of mass m orbits the planet X with a radius of orbit r.

a) Show that the linear speed v of the satellite is given by the expression (3 marks)

v=√GMrb) For this satellite,write down expressions,in terms ofG ,M ,m and r , for

i ) its kinetic energy, (2 marks)

ii ) its gravitational potential energy, (1 mark)

iii) its total energy. (2 marks)

c) The total energy of the satellite gradually decreases. State and explain the effect of this decrease on

i) the radius r of the orbit, (2 marks)

ii) the linear speed v of the satellite. (2 marks)

[Total: 12 marks]

Q8. An ideal gas in a cylinder has a volume of 9.5×10−4 m3 at a pressure of 2.60×105 Pa and a temperature of 297 K. The thermal energy required to raise the temperature by 1.00 K of 1.00 mol of the gas at constant volume is 45.0 J.The gas is heated at a constant volume such that the internal energy of the gas increases by 90.0 J.

a) Calculate

i) the amount of gas, in mol, in the cylinder, (2 marks)

ii) the rise in temperature of the gas. (2 marks)

b) Use your answer in (a)(ii) to show that the final pressure of the gas in the cylinder is 2.78×105 Pa. (1 mark)

[Total: 5 marks]


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Tunku Abdul Rahman University College Exam Paper