Section A [15 marks]

Answer all questions in this section.

1. Which of the following experimental techniques reduces the systematic error of the quantity being investigated? A Measuring the diameter of a wire repeatedly and calculate its average. B Adjusting the ammeter to remove its zero error before measuring a current. C Reading off the mass of an object directly from an electronic balance. D Timing a large number of oscillations to find a period. 2. In an experiment to determine the thickness of the glass of a boiling tube, the following readings were taken. Internal diameter, d1 = (2.064 ± 0.004 ) cm External diameter, d2 = (2.560 ± 0.004 ) cm The uncertainty in the thickness of the glass is A ± 0.002 cm B ± 0.004 cm C ± 0.008 cm D ± 0.016 cm 3. A steel ball is released from rest at a distance above a horizontal surface and is allowed to bounce. Which graph represents the variation with time, t of the acceleration, a?

a

t

a

A

a

t

a

B

a

t

a

C

a

t

a

D

4. A body A, of mass 8.0 kg moves directly towards a stationary body B, of mass 12 kg

and collide with it. They both then move off with the same velocity. If Av is the change

in the velocity of A and Bv is the change in the velocity of B, which of the following

statement is true?

A Kinetic energy is conserved and the magnitude of B

A

v

v

is

2

3

B Kinetic energy is conserved and the magnitude of B

A

v

v

is

3

2

C Momentum is conserved and the magnitude of B

A

v

v

is

2

3

D Momentum is conserved and the magnitude ofB

A

v

v

is

3

2

5. A small electric motor is used to raise a weight of 2.0 N at a constant speed of 20 cms-1 through a certain height. If the efficiency of the motor is 20%, what is the electrical power supplied to the motor? A 0.08 W B 0.80 W C 2.0 W D 200 W 6. Johar is playing with a toy car of mass 0.100 kg, and he lets the toy car travel along a track which contains a vertical circular loop of radius 0.10 m as shown in the diagram below.

What is the minimum speed of the car required at the top of the circular loop to prevent it from falling off the track? A 0.30 ms-1 B 0.99 ms-1 C 1.4 ms-1 D 10 ms-1

7. A ball is thrown at an angle above the horizontal. It lands on the ground after traveling a certain distance. Air resistance is negligible. Which of the following best shows the correct gravitational potential energy (GPE) , kinetic energy (KE) and total energy (TE) graphs for the ball? (Assume GPE to be zero on the Earth’s surface.)

8. Two satellites, A and B, orbiting around Earth have the same gravitational potential energy. Satellite A has a larger mass than satellite B. Which of the following statements is true? A Both satellites have the same period. B Both satellites have the same linear speed. C Satellite A is at a higher orbit than satellite B. D Satellite B is at a higher orbit than satellite A.

energy

time 0

KE GPE

TE

D

energy

time 0

GPE KE

TE

C

energy

time 0

KE GPE

TE

B

energy

time 0

GPE KE

TE

A

9. A pole of length 2 m has non-uniform composition, so that the centre of gravity is not at its geometrical centre. The pole is laid on supports across two weighing balances as shown in the diagram below. The balances which was previously set to zero recorded readings of 720 g and 480 g respectively.

Where is the centre of gravity of the pole from its geometrical centre?

A 5

1m to the left B

5

1m to the right

C 3

1m to the left D

3

1m to the right

10. A uniform, vertical wire is stretched by hanging a load from its lower end. Which of the following does not affect the strain in the wire? A the stress B its unstretched length C its cross-sectional area D the load applied 11. A container of fixed volume contains a mass m of an ideal gas at pressure p. The root mean square (r.m.s.) velocity of the molecules is c. A further mass m of the same gas is added into the container and the pressure rises to 2p. What is the final r.m.s. velocity of the molecules at pressure 2p?

A 2

c B c C 2c D 2c

2 m

pole

720 g 480 g

12. Two closed vessels X and Y contain equal masses of an ideal gas. X has a greater volume than Y. When the temperature changes, which of the following represents the

variation of the pressure (in Nm-2) of the gas in each vessel with temperature (in 0C)?

p/Nm-2

/ 0C

p/Nm-2

/ 0C

p/Nm-2

/ 0C

p/Nm-2

/ 0C

A B

C D

X

Y

X

Y

X

Y X

Y

13. An ideal gas is enclosed in a cylinder by a gas-tight, frictionless piston. The gas then undergoes a series of changes as shown in the figure below.

Which of the following statements is true? A There is no change in the internal energy of the gas. B Work is done on the gas. C The average kinetic energy of the gas molecules is the same at both states A and B. D Heat is gained by the gas.

1

2

3

4

0

2 4 6 8

Pressure / 105 Pa

Volume / 10-2

m3

A

B

14. Two metal rods of the same length and cross sectional area is connected end to end. The composite rod is insulated perfectly and its exposed ends are maintained at 100oC and 0oC as shown in the diagram (a) below. When equilibrium is achieved , the variation in temperature gradient with distance from the hot end of the composite rod is shown in diagram (b).

What is the temperature at the joint of the composite rod ?

A 33oC B 50oC C 67oC D 75oC 15. Some astronomical objects radiates as black bodies. These bodies are spherical where the surface temperature is inversely proportional to its radius. X and Y are such objects

where the radius of X is twice that of Y. Calculate Ybyemittedenergyofrate

Xbyemittedenergyofrate?

A 0.25 B 1.00 C 2.60 D 4.00

100oC 0oC

Insulation

Insulation

Joint

y

3y

Temperature gradient

distance

(a)

(b)

Section B [15 marks]

Answer all questions in this section.

16. The period of oscillation of a pendulum is given by the equation

g

lT 2

where l is the length of the pendulum and g is the acceleration of free fall. To determine g, a student obtained the following data : Period of oscillation = (0.910 ± 0.005) s Length of pendulum = (20.6 ± 0.1) cm

(a) Determine the percentage uncertainty in g [4 marks] (b) Express g together its associated uncertainty. [3 marks]

17. (a) State three assumptions of an ideal gas. [3 marks] (b) State in words how the temperature of an ideal gas is related to the energy of the molecules of the gas. [1 mark] (c) A plasma is a mixture of gas atoms, gas ions and electrons, all in thermal equilibrium. In a certain hydrogen plasma, the hydrogen atoms, hydrogen ions (protons) and electrons can be assumed to behave like the molecules of a mixture of three ideal gases. The r.m.s.

speed of the hydrogen ions in the plasma is found to be 6.0 x 104 ms-1.

(i) Determine the r.m.s. speed of the hydrogen atoms and electrons in the plasma.

[3 marks] (ii) Determine the temperature of the plasma. [2 marks]

Section C [30 marks]

Answer any two questions in this section. 18. (a) What do you understand by (i) the mass of a body (ii) the weight of a body Give an example

(iii) of an object that has no mass (iv) a situation where object that has mass but has no weight. [4 marks]

(b) A toy rocket consists of a plastic bottle which is partially filled with water. The space above the water contains compressed air, as shown in the diagram below.

At one instant during the flight of the rocket, water of density is forced through the nozzle of radius r at speed v relative to the nozzle. Determine in terms of , r and v, (i) the mass of water ejected per unit time from the nozzle. (ii) the rate of change of momentum of water. Hence show that the accelerating force F acting on the rocket is given by the expression

mgvrF 22

where m is the mass of the rocket and its contents at the instant considered. [6 marks]

Compressed air

Water

Nozzle

(c) The toy manufacturer recommends that the rocket should contain about 550 cm3 of

water before take-off. If the initial air pressure is 1.6 x 105 Pa , all of this water will be

expelled and the pressure is just reduced to atmospheric pressure as the last of the water is expelled. However , on one flight, the initial volume of water was 750 cm3 but the

initial air pressure in the rocket was still 1.6 x 105 Pa.

State , without calculation but with a reason, the effect of this increased volume of water on

(i) the initial thrust (ii) the initial resultant accelerating force (iii) the initial acceleration (iv) the final mass of the rocket and its contents, (v) the maximum height reached. [5 marks]

19.(a) (i) Define stress and strain for a wire. How are these quantities related to the Young’s modulus of the wire. [3 marks] (ii) Two wires are made from the same material. If one wire is longer and have a smaller diameter than the other, what can you deduce about the Young’s modulus of the wires. [1 mark] (b) (i) Explain the term plastic deformation of a wire. How is it used to differentiate materials that are ductile or brittle. [3 marks] (ii) Polymeric materials such as rubber and polythene have rather different behavior under stress. Sketch the stress-strain graph for rubber and polythene and explain their behaviors on elasticity. [4 marks]

(c) A load of 35.0 N applied to a wire of cross-sectional area 1.50 x 10-7

m2 and length 2.00 m causes an extension of 1.00 mm. Calculate (i) the stress on the wire (ii) the strain of the wire (iii) the energy stored per unit volume [4 marks]

20.(a) The simple microscopic model of an ideal gas may be used to derive the relation

2

3

1cp . By comparing this equation with the ideal gas equation RTpVm ,

find an expression for the temperature of a gas in terms of the average kinetic energy of the molecules and the Boltzmann constant. [6 marks] (b) (i)What is meant by a degree of freedom. [1 mark] (ii) Explain why different types of molecules have differing degrees of freedom at room temperature. [4 marks] (iii) State the Principle of Equipartition of Energy [1 mark]

(c) It is known that the ratio of the principle molar heat capacities of a gas, , is related

to the degrees of freedom by the relation f

21 where f is the degrees of freedom.

The value of for a certain diatomic gas is 1.40 at 300 K , but at 50 K it is 1.67. Calculate the number of degree of freedom at these temperatures. Suggest an explanation for the difference. [4 marks]

Values of Constants ( Nilai Pemalar)

Acceleration of free fall (Pecutan jatuh bebas) g = 9.81 m s-2 Avogadro constant (Pemalar Avogadro) NA = 6.02 x 1023 mol-1 Boltzmann constant (Pemalar Boltzmann) k = 1.38 x 10-23 J K-1 Gravitational constant (Pemalar gravity) G = 6.67 x 10-11 Nm2kg-2 Magnitude of electronic (Magnitud cas electron) e = 1.60 x 10-19 C charge Mass of the Earth (Jisim Bumi) ME = 5.97 x 1024 kg Mass of the Sun (Jisim Matahari) MS = 1.99 x 1030 kg

Molar gas constant (Pemalar gas molar) R = 8.31 J K-1 mol-1 Permeability of free space (Ketelapan ruang bebas) 0 = 4 x 10-7 Hm-1 Permittivity of free space (Ketelusan ruang bebas) 0 = 8.85 x 10-12 Fm-1

≈

36

1 x 10-9 F m-1

Planck constant (Pemalar Planck) h = 6.63 x 10-34 J s Radius of the Earth (Jejari Bumi) RE = 6.38 x 106 m Radius of the Sun (Jejari Matahari) RS = 6.96 x 108 m Rest mass of electron (Jisim rehat electron) me = 9.11 x 10-31 kg Rest mass of proton (Jisim rehat proton) mp = 1.67 x 10-27 kg Speed of light in free space (Laju cahaya dalam ruang bebas) c = 3.00 x 108 ms-1 Stefan-Boltzmann constant (Pemalar Stefan-Boltzmann) = 5.67 x 10-8 Wm-2K-4 Unified atomic mass unit (Unit jisim atom bersatu) u = 1.66 x 10-27 kg