Cambridge IGCSE Physics - 0625 - Core Paper 3 2021 Winter Zone 2

A cyclist travels to a friend’s house.
Fig. 1.1 shows the distance–time graph of the journey.

(a) Determine the distance travelled by the cyclist between points C and E.
distance travelled = .................................................. m [2]
(b) Describe the motion, if any, of the cyclist between points B and C. .................................. [1]
(c) State the section, AB, BC, CD or DE, of the graph in which the speed of the cyclist is the fastest. Give a reason for your answer.
section of graph ..................................................
reason ......................................................................................................................... [2]
(d) Calculate the average speed of the cyclist between points A and E. Include the unit in your answer.
average speed = ................................ unit ............... [4]

(a) A coin collector has 19 identical coins, as shown in Fig. 2.1.



Fig. 2.1

Fig. 2.2 shows one of the coins in the coin collector’s hand.



Fig. 2.2

The coin collector wants to check the thickness of one coin. She has a 30 cm ruler.

Describe how she can use the 30 cm ruler to determine the thickness of one coin accurately.
You may include a diagram if you wish.

[3 marks]

(b) The coin collector finds another coin. She thinks this coin is made of gold.

She performs an experiment to find the coin’s density.

She obtains the following results:

mass of coin = 52.5 g
volume of coin = 5.4 cm$^3$

(i) Show that the density of this coin is about 10 g/cm$^3$.

[3 marks]

(ii) The density of liquid mercury is 13.6 g/cm$^3$. State and explain whether the coin in (b)(i) floats on liquid mercury.

[1 mark]

Fig. 3.1 shows the vertical forces acting on a toy rocket as it leaves the ground.


(a) Calculate the size of the resultant vertical force on the rocket.

resultant force = ........................................................ N [2]

(b) Explain why the top of the rocket is pointed and has a smooth surface.

.......................................................................................................................
.......................................................................................................................
................................................................................................. [2]

(a) A teacher wants to measure the mass of a block of metal. She also wants to measure the length, width and height of the block.

Fig. 4.1 shows the block of metal.

[Image_1: Diagram of a block with dimensions labeled 'length', 'width', and 'height']

Complete each sentence using a word from the list.

balance barometer protractor ruler voltmeter

(i) To find the mass of the metal block, the teacher uses a ................................................. [1]

(ii) To measure the length, width and height of the metal block, she uses a ...................... [1]

(b) The mass of the block is 5000 g.

Calculate the weight of the block.

weight = ...................................................... N [3]

(c) Fig. 4.2 shows another block of metal on a solid surface.

[Image_2: Diagram of a block with dimensions 20 cm, 12 cm, and 2.0 cm on a solid surface]

(i) Calculate the area of the block of metal in contact with the solid surface.

area = .................................................. cm$^2$ [1]

(ii) The weight of the block of metal in Fig. 4.2 is 60 N.

Calculate the pressure of the block of metal on the solid surface.

pressure = ........................................ N/cm$^2$ [3]

(a) A student determines the centre of mass of a piece of wood. The wood is an irregular shape of constant thickness. He suspends the piece of wood from a nail as shown in Fig. 5.1. The wood is able to swing freely. The student suspends a weight on a thin string from the nail.

Fig. 5.1
Describe how to determine the centre of mass of the piece of wood in Fig. 5.1. You may draw a diagram to help your answer.
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................ [3]
(b) Fig. 5.2 shows a flat, symmetrical object. Indicate its centre of mass by drawing X in the correct position.

Fig. 5.2 [1]
(c) Fig. 5.3 shows a side view of a drinking-glass in two different positions, A and B.

Fig. 5.3
State which position, A or B, is more stable. Explain your answer.
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................ [2]

(a) A girl has eight objects made of different materials.
The materials have different electrical and magnetic properties.

a piece of copper wire a sheet of aluminium foil a glass rod an iron nail a piece of cotton cloth a wooden block a plastic strip a paper bag

Complete Table 6.1 by adding one object for each property. One is done for you.
Choose objects from the list. Each object may be used once, more than once or not at all.

Table 6.1

\begin{array}{|c|c|}\hline\text{property}&\text{object}\\\hline\text{electrical conductor}&\\\hline\text{electrical insulator}&\\\hline\text{non-magnetic material}&\text{a wooden block}\\\hline\text{magnetic material}&\\\hline\text{can be charged by rubbing with a cloth}&\\\hline\end{array}
[4]

(b) Fig. 6.1 shows three measuring instruments.
Write the name of each measuring instrument next to its diagram.
The measuring instruments are not drawn to scale.

[Image of three measuring instruments]

[3]

(a) Fig. 7.1 shows a candle underneath a thin, metal fan.

When the candle starts to burn, the fan starts to rotate around its support.
Explain what causes the fan to rotate.
.................................................................................................................................
.................................................................................................................................
................................................................................................................................. [3]
(b) Fig. 7.2 shows a bimetallic strip. It is made of two metals, steel and copper, fastened together.
The bimetallic strip is straight when the temperature is 25°C.

Fig. 7.3 shows the bimetallic strip when the temperature is 40°C.

(i) Draw the bimetallic strip when the temperature is 10°C. [1]
(ii) The bimetallic strip is used in a circuit, as shown in Fig. 7.4. The circuit is in a room.

The room temperature is 25°C.
State and explain any changes in the circuit as the temperature of the room rises above 40°C.
.................................................................................................................................
................................................................................................................................. [2]

Fig. 8.1 shows a simplified diagram of a geothermal power station.


(a) (i) State the energy source for a geothermal power station. ................................. [1]
(ii) Complete the sentence about useful energy transfer in the power station. The generator converts ................................. energy into ................................. energy. [2]

(b) (i) State two advantages of a geothermal power station compared to a coal-fired power station.
1 .......................................................................................................................
2 ....................................................................................................................... [2]

(ii) State one disadvantage of using geothermal energy rather than coal in a power station. ........................................................................................................................... [1]

(a) Fig. 9.1 shows a ray of light reflected by a plane mirror.

(i) State which angle, \(a, b, c\) or \(d\), is the angle of incidence. [1] 

(ii) State which angle, \(a, b, c\) or \(d\), is the angle of reflection  [1]

(b) Fig. 9.2 shows a road junction viewed from above. A plane mirror allows the drivers of the two cars A and B to see each other.

Fig. 9.2 shows a ray of light from car A travelling towards the plane mirror.

On Fig. 9.2, carefully continue this ray to show how the driver of car B can see car A. [2]

(a) Fig. 10.1 shows two resistors connected in series with a cell and three ammeters.

(i) State the physical quantity that an ammeter measures.
..................................................................................................................................... [1]
(ii) Indicate the correct statement about the readings $A_1$, $A_2$, and $A_3$ on the ammeters in Fig. 10.1.
Tick one box.

(a) Fig. 11.1 shows a magnet and a coil of wire connected to a galvanometer.

A student slowly moves the magnet into the coil. The pointer on the galvanometer moves to the left. This deflection shows that an electromotive force (e.m.f.) is induced in the coil.

State three ways of increasing the size of the e.m.f. in the coil.
1 ..............................................................................................................................
2 ..............................................................................................................................
3 .............................................................................................................................. [3]

(b) Fig. 11.2 shows a transformer.

(i) Name one material that is suitable for the core of the transformer.
.............................................................................................[1]

(ii) The primary coil has 1000 turns and its input is 240V a.c. The secondary coil has 50 turns.
Calculate the output voltage across the secondary coil.
output voltage = .................................................. V [3]

(a) State which radioactive emission is:

(i) the most penetrating $\text{.....................}$ [1]

(ii) the most ionising. $\text{.....................}$ [1]

(b) Explain the meaning of the term \textit{isotope}.

$\text{...............................................................................................................................}$

$\text{...............................................................................................................................}$ [2]

(c) The isotope iodine-131 is used in hospitals. A sample of iodine-131 is prepared for use.

The half-life of iodine-131 is 8 days.

Determine the fraction of iodine-131 remaining in the sample after 16 days.

fraction remaining $= \text{.....................}$ [2]