Pioneer 5116 Scphy Prelim 2009 Paper2

Section A (45 marks) Answer all questions in the spaces provided. 1

A motor car of mass 1500 kg moving at 20 ms-1 is brought to rest at a distance of 30 m when the driver steps on the brakes. A constant retarding force F acts on the car until it comes to a rest. The speed-time graph of the motor car is as shown in the diagram below.

v / m s-1

20

t/s 0

t1

(a)

Find t1 the time taken for the car to come to a complete stop.

[2]

(b)

Using the result from part (a), calculate the retardation or deceleration of the car. [2]

(c)

Calculate the retarding force F.

[2]

2

2

The diagram shows a block of mass 5 kg sliding from rest through a distance of 30 m down a frictionless slope.

30 m 5m 5 kg

(a)

Calculate the gravitational potential energy of the block before it slides down the slope. [2]

(b)

Determine the kinetic energy of the block at the bottom of the slope as shown in the diagram. [1]

(c)

Calculate the speed of the block just at the bottom of the slope.

(d)

On a separate occasion, an electric motor which is used to lift the block up the slope has a power output of 1.0 kW. Find the work done by the motor if the time taken is 0.5 hr. [2]

[2]

3

3

In an experiment to determine the boiling point of a liquid, a 0.12 kW immersion heater is used to heat the liquid. During the heating, the liquid was constantly stirred. The graph below shows how the temperature of the liquid changes with time for part of the heating process.

a)

Explain why the liquid is constantly stirred during the experiment.

[1]

________________________________________________________________

b)

i)

What happens to the liquid along BC of the graph?

[1]

________________________________________________________________

ii) Explain, in molecular terms, what has happened to the heat supplied by the heater along BC. [2] ________________________________________________________________

________________________________________________________________

4

4

The diagram shows a wave travelling across the surface of a lake. The wave causes a small cork across the surface of a lake. The wave causes a small cork (Z) to rise up and down, completing 12 oscillations in 3.0s.

1m 3m Fig. 5.1 Determine, (a)

the amplitude of the wave

[1]

(b)

the frequency of the wave

[2]

(c)

the speed of the wave

[2]

5

5

Sailors use sound waves to measure the depth of water beneath their ship. A pulse of sound is transmitted to the sea bed and returns to the ship. The figure below shows the arrangement.

path of pulse of sound

sea bed

(a)

Sound is a longitudinal wave. Explain what is meant by a longitudinal

wave.

[1]

________________________________________________________

________________________________________________________

(b)

The time taken for the sound pulse to reach the sea bed and then return to the ship is 0.10 s. The speed of sound in sea water is 1500 m/s. Calculate the depth of the sea.

(c)

[2]

State two differences between sound waves and electromagnetic waves.

[2]

________________________________________________________

________________________________________________________

6

6

(a)

Define the e.m.f. of a battery.

[1]

________________________________________________________ (b)

The circuit diagram shows a d.c. supply of negligible internal resistance connected to an arrangement of resistors. The current at three places in the circuit and the resistance of three of the resistors are given on the diagram.

V

1.0 Ω

R1 (i)

Calculate the potential difference across the 4.0 Ω resistor.

[1]

(ii)

Calculate the resistance of resistor R1.

[2]

(iii)

Calculate the effective resistance of circuit.

[2]

7

7

The diagram shows the wiring inside an electric iron. earth wire

live wire heating element

metal plate neutral wire (a)

Why is the heating element made of tungsten metal?

[1]

________________________________________________________ ________________________________________________________

(b)

What is the purpose of connecting the earth wire to the metal plate of the iron?

[1]

________________________________________________________ ________________________________________________________

(c)

What is the colour of the neutral wire?

[1]

________________________________________________________

8

(d)

The iron has a power rating of 1500 W and is connected to a 240 V mains supply. (i)

Calculate the current passing through the iron when in use.

(ii)

Fuses of rating 1 A, 2 A, 5 A, 10 A and 13 A are available. Which fuse should be used for the iron?

(iii)

[1]

[1]

If electricity costs 15 ¢ per kWh, what is the cost of using the iron for 10 hrs?

[2]

9

8

(i)

(a)

Determine the polarity p and q of the following experiments.

(ii)

p

[2]

S N q

Polarity of p =

(b)

Polarity of q =

The diagram below shows a magnet attracting two steel bars on both poles. Magnet N

Steel

(i)

S

Steel

Explain in terms of induced magnetism, why this happens.

[2]

_____________________________________________________

_____________________________________________________

(ii)

When the steel bars are detached from the magnet and placed close together, it is found that they would still attract each other. Explain why this is so. [1]

____________________________________________________________ ____________________________________________________________

10

Section B (20 marks) Answer any TWO questions. Write your answers on the lined paper provided and, if necessary, continue on separate answer paper.

9

(a) The diagram shows a model of a Bunsen burner in the form of a thin piece of card. The model has small holes drilled through it at K, L and M.

Fig. 10.1 Explain briefly how you would determine the position of the centre of gravity of the model. (b)

[3]

The diagram shows a cross section through the centre of a triangular prism. G shows the position of the centre of gravity of the prism.

The prism is laid on one of its rectangular faces on a horizontal table. On which side, PQ or QR or RP, should the prism be placed for maximum stability? State your reasons for your answer.

[3]

11

(c)

The diagram below shows the essential parts of a hand winch.

force

handle

2m

load 0.1 m cable drum

The winch is used to move a load of 3000 N through a horizontal distance of 0.15 m towards the drum. Calculate

(i) (ii)

the minimum force required to turn the drum. the work done by the load.

[2] [2]

12

10

The diagram below shows a light ray travelling from air through a piece of glass and then into Liquid L before emerging into air again.

50o

Air Glass

Liquid L

Air

32o

a

50o

(a)

Calculate the refractive index of the piece of glass.

[2]

(b)

Find the angle a if the refractive index of Liquid L is 1.65.

[2]

(c)

Given that the speed of light in air is 3 x 108 m/s, calculate the speed of [2] light in Liquid L.

13

(d) The diagram shows an object (O) placed in front of a thin converging lens. The positions of the focal points are marked F.

O F

(i)

(ii)

F

On the diagram, draw two light rays from the object to obtain the position of the image. Label the image “I”.

[3]

[1]

If the distance of the object from the lens is reduced to be less than the focal length, state whether whether you will obtain a real or virtual image.

14

11

The lamps in a house are connected in parallel to the mains supply. (a)

Copy the diagram on your answer sheet and draw three lamps and their switches connected to the mains supply.

[2]

fuse live

neutral

Figure 11.1 (b)

Each lamp is labelled 230 V, 30 W. Calculate the current in one lamp when it is operating correctly.

(c)

[1]

(i)

State the purpose of a fuse and explain how it works. [2]

(ii)

Explain why the fuse is placed in the live wire rather than the neutral wire.

(iii)

[1]

The fuse has a rating of 1 A. Calculate the maximum number of lamps that can be connected and switched on without the fuse blowing. Each lamp is in parallel with the power supply.

(d)

[2]

The wires supplying electric current to a water heater carry a larger current and are thicker than those supplying current to the lamps. Explain why the wires are made thicker.

[2]

END OF PAPER

15

16