A2 Multiple Choice Selection 6
Q1.
A baby bouncer consisting of a harness and elastic ropes is suspended from a doorway. When a baby of mass 10 kg is placed in the harness, the ropes stretch by 0.25 m. When the baby bounces, she starts to move with vertical simple harmonic motion. What is the time period of her motion?
A       1.0 s
B       2.1 s
C       2.3 s
D       3.1 s
(Total 1 mark)
Q2.
An initially uncharged capacitor of capacitance 10 µF is charged by a constant current of 200 µA. After what time will the potential difference across the capacitor be 2000 V?
A       50 s
B     100 s
C     200 s
D     400 s
(Total 1 mark)
Q3.
Which one of the following is not an assumption about the properties of particles in the simple kinetic theory?
 
A	< c2 > is the average speed of the particles	
B	The forces between the particles are negligible except when particles collide	
C	The time spent by particles in collision is negligible compared with the time spent between collisions	
D	The volume of the particles is negligible compared to the volume of the container	
(Total 1 mark)

Q4.
Two identical positive point charges, P and Q, separated by a distance r, repel each other with a force F. If r is decreased so that the electrical potential energy of Q is doubled, what is the force of repulsion?
A      0.5 F
B      F
C      2F
D      4F
(Total 1 mark)
Q5.
What is the angular speed of a satellite in a geo-synchronous orbit around the Earth?
A       7.3 × 10–5 rad s–1
B       2.6 × 10–1 rad s–1
C       24 rad s–1
D       5.0 × 106 rad s–1
(Total 1 mark)
Q6.
At a certain temperature, the root-mean-square speed of the molecules of a fixed volume of an ideal gas is c. The temperature of the gas is changed so that the pressure is halved. The root-mean-square speed of the molecules becomes
A       
B       
C       
D       2c
(Total 1 mark)

Q7.
The fusion of two deuterium nuclei produces a nuclide of helium plus a neutron and liberates 3.27 MeV of energy. How does the mass of the two deuterium nuclei compare with the combined mass of the helium nucleus and neutron?
A       It is 5.8 × 10−30 kg greater before fusion.
B       It is 5.8 × 10−30 kg greater after fusion.
C       It is 5.8 × 10−36 kg greater before fusion.
D       It is 5.8 × 10−36 kg greater after fusion.
(Total 1 mark)
Q8.
The mass of the nuclear fuel in a nuclear reactor decreases at a rate of 1.2 × 10−5 kg per hour.
Assuming 100% efficiency in the reactor what is the power output of the reactor?
A       100 MW
B       150 MW
C       200 MW
D       300 MW
(Total 1 mark)
Q9.
A horizontal straight wire of length 0.30 m carries a current of 2.0 A perpendicular to a horizontal uniform magnetic field of flux density 5.0 × 10–2 T. The wire ‘floats’ in equilibrium in the field.
 
What is the mass of the wire?
A       8.0 × 10–4 kg
B       3.1 × 10–3 kg
C       3.0 × 10–2 kg
D       8.2 × 10–1 kg
(Total 1 mark)

Q10.
A bar magnet is pushed into a coil connected to a sensitive ammeter, as shown in the diagram, until it comes to rest inside the coil.
 
Why does the ammeter briefly show a non-zero reading?
A       The magnetic flux linkage in the coil increases then decreases.
B       The magnetic flux linkage in the coil increases then becomes constant.
C       The magnetic flux linkage in the coil decreases then increases.
D       The magnetic flux linkage in the coil decreases then becomes constant.
(Total 1 mark)

Mark schemes
Q1.
A
[1]
Q2.
B
[1]
Q3.
A
[1]
Q4.
D
[1]
Q5.
A
[1]
Q6.
C
[1]
Q7.
A
[1]
Q8.
D
[1]
Q9.
B
[1]
Q10.
B
[1]