PA04 June 2003 SECTION A Multi-choice: You are to select the most appropriate answer in each case. You are advised to spend approximately 30 minutes on this section.
1. A particle, whose equilibrium position is at Q. is set into oscillation by being displaced to P, 50mm from Q, and then released from rest. Its subsequent motion is simple harmonic, but subject to damping.
On the first swing, the particle comes to rest momentarily at R, 45 mm from Q.
During this first swing, the greatest value of the acceleration of the particle is when it is at A P. B Q. C R. D P and R.
2 A particle of mass 5.0 x 10-3kg performing simple harmonic motion of amplitude 150mm takes 47s to make 50 oscillations. What is the maximum kinetic energy of the particle?
A 2.0 x 10-3 J B 2.5 x 10-3 J C 3.9 x 10-3 J D 5.0 x 10-3 J
3 When the length of a simple pendulum is decreased by 600 mm, the period of oscillation is halved. What is the original length of the pendulum?
A 800 mm B 1000mm C 1200mm D 1400mm
4 A wave of frequency 5 Hz travels at 8 kms-1 through a medium. What is the phase difference, in radians, between two points 2 km apart?
A 0 B p/2 C p D 3 p/2
5 A source emits light of wavelength 600 nm as a train of waves lasting 0.01ms. How many complete waves are sent out? speed of light = 3 x 108 ms-1
A 5 x 106 B 18 x 107 C 5 x 109 D 5 x 1022
6 Interference fringes, produced by monochromatic light are viewed on a screen placed a distance D from a double slit system with slit separation s. The distance between the centres of two adjacent fringes (the fringe separation) is w. If both s and D are doubled, what will be the new fringe separation?
A w/4 B w C 2w D 4w
7 A narrow beam of monochromatic light falls on a diffraction grating at normal incidence. The second order diffracted beam makes an angle of 45° with the grating. What is the highest order visible with this grating at this wavelength?
A 2 B 3 C 4 D 5
8 A 10 mF capacitor is charged to 10 V and then discharged completely through a small motor. During this process, the motor lifts a weight of mass 0.10kg. If 10% of the energy stored in the capacitor is used to lift the weight, through what approximate height will the weight be lifted?
A 0.05 m B 0.10 m C 0.50 m D 1.00 m
9 A capacitor of capacitance 15 mF is fully charged and the potential difference across its plates is 8.0 V. It is then connected into the circuit as shown.
The switch S is closed at time t = 0. Which one of the following statements is correct?
A The time constant of the circuit is 6.0 ms.
B The initial charge on the capacitor is 12 mC.
C After a time equal to twice the time constant, the charge remaining on the capacitor is Qoe2, where Q0 is the charge at time t = 0.
D After a time equal to the time constant, the potential difference across the capacitor is 2.9 V.
10 A fairground roundabout makes nine revolutions in one minute. What is the angular speed of the roundabout?
A 0.15 rad s-1 B 0.34 rad s-1 C 0.94 rad s-1 D 2.1 rad s-1
11
A small mass is placed at P on a horizontal disc which has centre O. The disc rotates anti-clockwise about a vertical axis through O with constant angular speed. Which one of the following describes the force which keeps the mass at rest relative to the disc?
A the weight of the mass B a frictional force directed away from O C a frictional force directed towards O D a frictional force directed from P to Q
12 The force between two point charges is F when they are separated by a distance r. If the separation is increased to 3r what is the force between the charges?
A F 3r
B F 9r
C F 3
D F 9
13
Two parallel metal plates of separation a carry equal and opposite charges. Which one of the following graphs, A to D, best represents how the electric field strength E varies with the distance x in the space between the plates?
14 In a thermal reactor, induced fission is caused by the 23592U nucleus capturing a neutron, undergoing fission and producing more neutrons. Which one of the following statements is true?
A To sustain the reaction a large number of neutrons is required per fission. B The purpose of the moderator is to absorb all the heat produced. C The neutrons required for induced fission of 23592U should be slow neutrons. D The purpose of the control rods is to slow down neutrons to thermal speeds.
15 Artificial radioactive nuclides are manufactured by placing naturally-occurring nuclides in a nuclear reactor. They are made radioactive in the reactor as a consequence of bombardment by A a particles. B b particles. C protons. D neutrons.
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