Qss 5116 Scphy P2 Prelim 09

QUEENSWAY SECONDARY SCHOOL PRELIMINARY EXAMINATION 2009 SCIENCE (5152) PAPER 2 PHYSICS Level:

SEC. 4E / 5 NA

Time : 1 h 15 mins Total Marks: 65

Name/Index No.:

(

)

Class:

READ THESE INSTRUCTIONS FIRST Write your name, Class and Index No. above and on any separate answer papers used. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs, tables or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Section A [45 marks] Answer all questions. Write your answers in the spaces provided on the question paper. Section B [20 marks] Answer any two questions. Write your answers on the lined paper provided and, if necessary, continue on separate answer paper. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question.

FOR EXAMINER’S USE Section A Section B

TOTAL

This Question Paper consists of 14 printed pages. [Turn over] 1

Section A Answer all the questions. Write your answers in the spaces provided on the question paper. 1

The figure below shows the speed of a car after it started from rest on a straight level road. The mass of the car is 1000 kg. 10 8 6 speed 4 in m/s 2 0 0

(a)

1

2

3

5 4 time in s

6

7

8

9

10

11

How does the graph indicate that the car had constant acceleration during the first four seconds? ……………………………………………………………………… [1]

(b)

What was the acceleration during the first four seconds?

acceleration = ……………… m/s2 [2] (c)

How far did the car move in the last three seconds?

distance = ……………… m [2] (d)

During which time interval was the acceleration decreasing? …………………………………………………………………………… [1]

(e)

How big was the resultant force acting on the car three seconds after starting?

force = ……………… N [2]

2

2

A box of mass 20 kg is being pushed across a rough floor at a constant speed of 0.2 m/s. The box slides without tipping. A constant horizontal force of 80 N is being applied. Box 80 N

Rough floor (a)

(i)

Polished floor

State the size of the frictional force acting on the box and explain how you obtain your answer. ………………………………………………………………...... …………………………………………………………………... …………………………………………………..…………… [3]

(ii)

What is the direction of the frictional force? ……………………………………………………………

(b)

[1]

The box is then pushed across a polished surface as shown in the figure above. The same force of 80 N is applied to the box and the box accelerates at 1.5 m/s2. Calculate for the box (on the polished section of the floor), (i)

the force causing the acceleration.

force = ……………… N [2] (ii)

the size of the frictional force.

force = ……………… N [1]

3

3

(a)

What is meant by centre of gravity? ……………………………………………………………………

(b)

[1]

Why is it advisable for passengers not to stand at the upper deck of a double decker bus? …………………………………………………………………… ……………………………………………………………………

4

[2]

The diagram below shows a fountain that can be used in a garden.

The pump raises the water in the fountain to a height of 1.5 m. The mass of water pumped every minute is 40 kg. (a)

State one form of energy gained by the water. ……………………………………………………………………

(b)

[1]

Calculate how much energy is gained by 40 kg of water when it is raised through a vertical height of 1.5 m. The gravitational field strength is 10 N/kg.

energy = ………………J [2]

4

5

The diagram shows a ray of light travelling from air into a liquid L and through a piece of glass. (Diagram is not drawn to scale.)

Air

Liquid L

Glass

Air

(a)

Which has a higher refractive index, liquid L or the glass? Explain your answer. ………………………………………………………………............... …………………………………………………………………....... [2]

(b)

If the refractive index of the glass is 1.52, calculate angle a.

angle = ………………° [2]

5

6

Radio waves and microwaves are parts of the electromagnetic spectrum. They are often used to transmit communication signals. For example, radio waves are used to transmit television signals whereas microwaves are used in Bluetooth devices. (a)

(i)

Insert radio waves and microwaves with letters R and M respectively into Fig. 6 in regions which represent the electromagnetic spectrum. [1]

Visible light violet red

Fig. 6

(ii)

Indicate with an arrow on Fig. 6, the direction of increasing frequency of the electromagnetic spectrum. [1]

(b)

Infra-red is another component of the electromagnetic spectrum. It is used in many common electronic devices. State a device that makes use of infra red. ……………………………………………………………………… [1]

(c)

State two properties in which infrared, microwaves and radio waves have in common. 1. …………………………………………………………………… ………………………………………………………………………… 2. ……………………………………………………………….….… …………………………………………….…………………..……. [2]

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7

Fig. 7.1 shows a small dome-shaped house built by Eskimos from blocks of hard snow as a temporary shelter (which is called igloo). The cross section of the igloo is shown in Fig. 7.2. Air hole

sleeping area

sleeping area

Igloo Fig 7.1 (a)

Fig 7.2

cold sink

State one thermal property of the hard snow blocks that make them suitable for building igloo. ……………………………………………………………………… [1]

(b)

What are the two main processes of heat transfer from the residents' bodies to the air inside the igloo? ……………………………………………………………………… [2]

(c)

State the function of the air hole in the roof of the igloo. ……………………………………………………………………… [1]

7

8

A strip of plastic is rubbed with a piece of dry cloth and then hung over an insulating rod as shown in the diagram.

(a)

What happens to the plastic strip when it is rubbed with a dry cloth? ……………………………………………………………………… [1]

(b)

Why do the ends of the strip diverge? ………………………………………………………………………… ……………………………………………………………………… [2]

9

Fig. 9 shows a coil connected to d.c.12.0 V. A compass is placed between the coil and a permanent magnet. compass

Fig. 9 (a)

Draw the direction of the compass needle when the switch is opened. [1]

(b)

Draw the magnetic field lines around the coil when the switch is closed and indicate their directions. [2]

8

(c)

The battery is replaced by an a.c. supply. Describe and explain what will happen when the switch is closed. …………………………………………………………………………. …………………………………………………………..………… [2]

10

In the circuit shown below, the resistances of the ammeters may be ignored.

Explain each of the following observations. (a)

When switch S is closed, current through A1 is less than that through the 4 Ω resistor. …………………………………………………………..………… [1]

(b)

When switch S is opened, the current through A2 falls. …………………………………………………………..………… [1]

(c)

When switch S is opened, the current through each ammeter is the same. …………………………………………………………..………… [1]

9

Section B Answer any two questions. Write your answers on the lined paper provided and, if necessary, continue on separate answer paper. 11

A man is hanging out laundry for drying. The pants, shirt and towel have masses 2.10 kg, 0.40 kg and 0.20 kg respectively. The centre of mass of the towel, shirt and pants is 0.60 m, 1.10 m, and 1.60 m away from the near end of the man.

Fig. 11.1 (a)

State the Principle of Moments.

[1]

(b)

Is it wise for the man to arrange the clothing as shown in Fig. 11.1? Give your reason(s). [2]

(c)

Suggest a reason why the man is holding the rod with his hands as far apart as possible. [2]

Fig. 11.2 (d)

The man puts his left hand at a distance of 0.30 m from the near end while his right hand is holding the near end of the rod as shown in Fig. 11.2. (i)

What is the direction of the force exerted by each hand? [1]

10

(ii)

12

(e)

Describe how the clothes should be rearranged so that a minimum force is exerted by his left hand. [1]

(a)

Describe briefly the differences between the motions of the molecules of ice, water and steam.

[3]

(b)

State and explain what happens to the molecules in a block of ice when the temperature of the ice is increased but the ice does not melt. [2]

(c)

This question is about the rate of evaporation from a pool of water. What effect if any, does the statements below have on the rate of evaporation? (i) (ii) (iii)

(d) 13)

Calculate the force exerted by each hand acting perpendicularly to the rod. [3]

Increase in temperature of water. Increase in surface area of water. Increase of wind speed over water.

[1]

Explain your answers in (c) using kinetic theory.

[4]

Bill is setting up his new computer system at home. He plugs in the power supply for the CPU, monitor, printer and scanner into one single wall socket as shown.

The power ratings of each electrical appliance are: CPU : 750 W, 240 V Monitor : 120 W, 240 V

Printer : 240 W, 240 V Scanner : 360 W, 240 V

(a)

In terms of d.c. circuit connection, the method above is similar to a parallel or series circuit? Explain. [2]

(b)

Calculate the resistances of the four appliances.

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[2]

(c)

Bill's setup can be simplified with a simple circuit diagram. Draw in the space below the circuit diagram of the four appliances connected to the wall circuit. Use fixed resistors to represent the four appliances, and label the resistors according to the following: R1: CPU, R2: Monitor, R3: Printer, R4: Scanner [1]

(d)

Calculate the effective resistance of the circuit.

(e)

By comparing the effective resistance in the circuit when all four appliances are connected to the wall socket and if only the scanner is connected, describe the effect this will have on the cables. [3]

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[2]

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