Cambridge IGCSE Physics - 0625 - Core Paper 3 2021 Summer Zone 3

Fig. 1.1 shows the speed–time graph for a car travelling along a road.

(a) Determine the distance travelled by the car between 30 s and 60 s.

distance travelled = ...................................................... m [3]

(b) The distance travelled by the car between 60 s and 110 s is 460 m.
Calculate the average speed of the car between 60 s and 110 s.

average speed = ..................................................... m/s [4]

(c) Describe the motion of the car between 30 s and 60 s.
..................................................................................................................................................... [1]

(d) Describe the motion of the car between 60 s and 80 s.
..................................................................................................................................................... [1]

[Total: 9]

(a) A scientist has a measuring cylinder, a beaker of sea water and an electronic balance. Describe an experiment to determine the density of the sea water. Include any equations in your answer.
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................................................................................................................. [5]
(b) A plank of wood floats on the sea.
Explain why the wood floats.
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................................................................................................................. [1]
[Total: 6]

(a) A girl and her brother sit on opposite sides of a see-saw as shown in Fig. 3.1.
(i) Calculate the girl's moment about the pivot and show that it is close to 460 Nm. [3]
(ii) The see-saw is balanced horizontally.
Calculate the weight $W$ of the brother.
$W$ = ................................................ N [3]

(b) The weight of the girl in Fig. 3.1 is 240 N.
Calculate the mass of the girl. Include the unit in your answer.
mass of girl = ....................... unit ......................... [4]

(a) A power station burns fossil fuel to produce electrical energy.
(i) State the form of the energy stored in the fuel.
............................................................................................................................................................... [1]
(ii) Some of the energy stored in the fuel is \textit{not} converted to electrical energy.
Suggest how energy is wasted in the generator.
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............................................................................................................................................................... [2]

(b) Solar panels produce electrical energy.
State \textit{two} advantages and \textit{two} disadvantages of using solar panels, rather than fossil fuels, to produce electrical energy.

advantages
1. ..........................................................................................................................................................
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2. ..........................................................................................................................................................
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disadvantages
1. ..........................................................................................................................................................
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2. ..........................................................................................................................................................
............................................................................................................................................................... [4]

(a) Fig. 5.1 shows a tractor and a car of the same weight.

Fig. 5.1

The vehicles drive over the same soft ground.

Explain why the car sinks into the soft ground but the tractor does not sink.
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............................................................................................................................... [3]

(b) The car driver measures the pressure of the air in a car tyre when the air is cool.

The Sun heats the air in the tyre. The driver measures the pressure of the air in the tyre when the air is warm.

The pressure of the air in the warm tyre is greater.

Explain the increase in the pressure of the air in the tyre. Use ideas about air molecules.
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............................................................................................................................... [3]

(a) Three rods are identical in size and shape, but each rod is made from a different material. On one end of each rod is a pin held in place by wax. The wax melts when it is warm.
The rods are placed on a block of wood and heated equally by a Bunsen burner as shown in Fig. 6.1.

Fig. 6.1
(i) State the process of thermal energy transfer through the rods.
............................................................................................................................. [1]
(ii) Explain how the arrangement in Fig. 6.1 can show which rod transfers thermal energy the most quickly.
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(b) (i) State the process by which infrared waves transfer thermal energy.
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(ii) State the process of thermal energy transfer which does not require a medium.
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(c) Fig. 6.2 shows a heater for warming a room. When there is hot water in the heater, the thermal energy of the water transfers to the room.

Fig. 6.2
The shiny foil on the wall increases the efficiency of the heater.
Explain how the shiny foil increases the efficiency of the heater.
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............................................................................................................................. [2]

This question is about the electromagnetic spectrum.

(a) (i) State the name of a region of the electromagnetic spectrum which has longer wavelengths than visible light.
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[1]

(ii) State the name of a region of the electromagnetic spectrum which has shorter wavelengths than visible light.
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[1]

(iii) Electromagnetic waves are travelling through a vacuum. Indicate the property that is always the same for all the waves.
Tick (✓) one box.

[Table_1]

frequency
speed
amplitude
[1]

(iv) Indicate the correct statement about the nature of electromagnetic waves.
Tick (✓) one box.

[Table_2]

All electromagnetic waves are transverse.
All electromagnetic waves are longitudinal.
Some electromagnetic waves are transverse and some are longitudinal.
[1]

(v) Indicate the correct statement about the action of electromagnetic waves.
Tick (✓) one box.

[Table_3]

They transfer energy from one place to another.
They transfer atoms from one place to another.
They transfer molecules from one place to another.
[1]

(b) State the type of electromagnetic radiation used:

(i) for a remote controller to operate a television
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[1]

(ii) in a hospital to produce an image of broken bones.
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[1]

[Total: 7]

(a) Fig. 8.1 shows a ray of light incident on a plane mirror.

(i) State which angle, a, b or c, is the angle of incidence.
angle of incidence = .................................................. [1]
(ii) State the name of the line labelled X.
................................................................ [1]
(iii) The mirror reflects the ray of light.
On Fig. 8.1, draw the reflected ray. [2]

(b) Fig. 8.2 shows a ray of red light travelling through a semicircular glass block.

(i) Fig. 8.3 shows another ray of red light entering the semicircular glass block at 60°. Continue the path of this ray through the glass block and into the air.
[2]
(ii) Fig. 8.4 shows another ray of red light entering the semicircular glass block at 20°. Continue the path of this ray through the glass block and into the air.
[2]

(a) Fig. 9.1 shows two uncharged balloons suspended from a beam by light thread.

The balloons are close to each other but not touching.
In the box below, draw the position of the balloons when they both have a positive charge.


[1]

(b) Table 9.1 includes a list of materials.
State whether each material is an electrical conductor or an electrical insulator.
The first example is done for you.

[Table_1]
material | conductor or insulator
copper | conductor
rubber |
wood |
iron |
gold |
[2]

(c) An uncharged cloth rubs an uncharged plastic rod. The cloth becomes positively charged and the plastic rod becomes negatively charged.
Explain how the cloth becomes positively charged.
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[3]

[Total: 6]

(a) Fig. 10.1 shows the circuit symbols for three electrical components.
Draw a line from each circuit symbol to the correct electrical component.

Fig. 10.1

(b) Fig. 10.2 shows a circuit consisting of a battery, a fixed resistor and an ammeter.

Fig. 10.2
(i) A voltmeter is connected in the circuit to measure the potential difference (p.d.) across the fixed resistor.
By drawing on Fig. 10.2, show how the voltmeter is connected. Use the correct circuit symbol for the voltmeter. [2]
(ii) The potential difference (p.d.) across the fixed resistor is 11.5 V. The reading on the ammeter is 0.25 A.
Calculate the resistance of the fixed resistor.
Include the unit in your answer.
$$ ext{resistance = .................... unit ...................} $$ [4]

(a) A nucleus of nitrogen-13 has the nuclide notation: $^{13}_{7}N$.
Determine:
(i) the number of protons in one nucleus of nitrogen-13 .................................................. [1]
(ii) the number of neutrons in one nucleus of nitrogen-13 ................................................. [1]
(iii) the number of electrons in one neutral atom of nitrogen-13. .......................................... [1]
(b) Fig. 11.1 shows a counter measuring the radioactivity of a sample of nitrogen-13.

Fig. 11.1
The counter shows the count rate in counts per minute.
Table 11.1 shows the count rate every 5 minutes.
[Table_1]
Table 11.1
$$\begin{array}{|c|c|} \hline \text{time/min} & \text{count rate due to nitrogen-13} \\ \text{counts/min} \\ \hline 0 & 300 \\ 5 & 212 \\ 10 & 150 \\ 15 & 106 \\ 20 & 75 \\ 25 & 53 \\ \hline \end{array}$$
Calculate the half-life of nitrogen-13 using information from Table 11.1.
half-life of nitrogen-13 = ................................................ min [2]
[Total: 5]