CIE iGCSE Co-Ordinated Science P3.2.1 Reflection of light Exam Style Questions Paper 3
Question
(a) A cyclist is riding a bicycle around a circular track.
The length of the track is 400m.
The cyclist completes five laps of the track.
The time taken for each lap is measured and recorded in Table 12.1.
(i) Calculate the average time for one lap.
average time for one lap = ………………………………………………. s
(ii) The air in the tyres of the bicycle warms up during the ride.
Describe how the motion of the molecules of the gas in the tyres changes during the ride.
………………………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………….
(iii) Select the correct word from the list to complete each sentence.
solids liquids gases
………………………… have no definite shape or volume.
………………………… have a definite volume but take the shape of the container.
(b) Fig. 12.1 shows a cyclist near a road junction.
A car driver at the junction can see the reflection of the cyclist in a plane mirror.
The ray of light shown allows the car driver to see the cyclist approaching the junction.
(i) On Fig. 12.1, draw an arrow on the ray of light to show the direction of travel of the ray of light.
(ii) On Fig. 12.1, label the angle of incidence with the letter i.
(c) The bicycle is left outside on a sunny day. Energy from the Sun heats the metal frame of the bicycle.
(i) State the method of energy transfer between the Sun and the Earth.
……………………………………………………………………………………………………………………
(ii) State the method of energy transfer through the frame of the bicycle.
……………………………………………………………………………………………………………………
(iii) Describe a simple way of testing whether the frame of the bicycle is made from steel or from aluminium.
……………………………………………………………………………………………………………………
…………………………………………………………………………………………………………………….
▶️Answer/Explanation
Ans: 12(a)(i) 35.3 (s) ;
12(a)(ii) molecules move faster ;
12(a)(iii) gases and
liquids
both correct – 1 mark ;
12(b)(i) arrow drawn going away from cyclist / towards driver ;
12(b)(ii) angle of incidence correctly labelled ;
12(c)(i) radiation ;
12(c)(ii) conduction ;
12(c)(iii) use a magnet ;
steel will be attracted (to magnet) ; ORA
Question
(a) Fig. 3.1 shows four forces acting on a submarine. The submarine is moving underwater at a constant speed.
State which force A, B, C or D is the weight of the submarine. (Sub-topic – P1.5.1)
▶️Answer/Explanation
Answer: C
Explanation: The weight of the submarine is the force due to gravity acting downward. In the diagram, force C is directed downward, indicating that it represents the weight of the submarine.
(b) The submarine travels 36 km in 2 hours. Calculate the speed of the submarine in m/s. (Sub-topic – P1.2)
▶️Answer/Explanation
Answer: 5 m/s
Explanation:
- Convert 36 km to meters: \( 36 \text{ km} = 36,000 \text{ m} \).
- Convert 2 hours to seconds: \( 2 \text{ hours} = 2 \times 60 \times 60 = 7,200 \text{ s} \).
- Calculate speed using the formula \( \text{speed} = \frac{\text{distance}}{\text{time}} \): \( \text{speed} = \frac{36,000}{7,200} = 5 \text{ m/s} \).
(c) The submarine is powered by a small nuclear reactor. Ionising radiation is released in the reactor. The reactor must be shielded to protect the crew from this radiation. (Sub-topic – P5.2.2)
(i) State how exposure to ionising radiation can affect the human body.
▶️Answer/Explanation
Answer: Cancer / cell mutation
Explanation: Ionising radiation can damage the DNA in cells, leading to mutations that may cause cancer or other harmful effects on the body.
(ii) Suggest a material which can be used to shield a nuclear reactor and stop \(\alpha\)-radiation and \(\beta\)-radiation escaping.
▶️Answer/Explanation
Answer: Lead
Explanation: Lead is a dense material that is effective at blocking \(\alpha\) and \(\beta\) radiation due to its high atomic number and density.
(d) Plutonium-239 (Pu-239) is the nuclear fuel used by the submarine. Pu-239 has a half-life of 24,000 years. A small sample of Pu-239 has a mass of 1.0 g. Calculate the mass of Pu-239 remaining after 96,000 years. (Sub-topic – P5.2.4)
▶️Answer/Explanation
Answer: 0.0625 g
Explanation:
- Determine the number of half-lives in 96,000 years: \( \frac{96,000}{24,000} = 4 \) half-lives.
- Calculate the remaining mass after each half-life: \( 1.0 \text{ g} \rightarrow 0.5 \text{ g} \rightarrow 0.25 \text{ g} \rightarrow 0.125 \text{ g} \rightarrow 0.0625 \text{ g} \).
(e) When it is under the water, the submarine uses a periscope to view a ship on the surface of the sea. Fig. 3.2 shows a simple periscope.
On Fig. 3.2, draw a ray of light from the ship to the observer’s eye to show what happens to the light ray as it passes through the periscope. (Sub-topic – P3.2.1)
▶️Answer/Explanation
Answer: The light ray should reflect off the top mirror and then the bottom mirror before reaching the observer’s eye.
Explanation: In a periscope, light from the ship enters the top mirror, reflects downward to the bottom mirror, and then reflects into the observer’s eye. The ray should be drawn to show these two reflections.
Question
An astronomer observes a large meteorite, a rock from outer space. The astronomer uses a telescope which contains mirrors.
Fig. 12.1 shows the image of the meteorite seen in the mirror by the astronomer.
(a) Select two words or phrases from the list to describe the characteristics of an image formed by a single plane mirror. (Sub-topic – P3.2.1)
▶️Answer/Explanation
The two characteristics of an image formed by a single plane mirror are:
- same size
- upright
(b) The meteorite enters the Earth’s atmosphere.
Fig. 12.2 is a speed-time graph for the meteorite as it approaches Earth.
(i) On Fig. 12.2, label with an S a point when the meteorite is slowing down. (Sub-topic – P1.2)
▶️Answer/Explanation
The meteorite slows down when it experiences air resistance, which occurs after it reaches its maximum speed. Label a point on the graph where the speed starts to decrease.
S somewhere between 5 s and 12 s
(ii) State the form of energy lost by the meteorite as it slows down. (Sub-topic – P1.6.1)
▶️Answer/Explanation
The meteorite loses kinetic energy as it slows down due to air resistance and friction with the atmosphere.
(iii) Use Fig. 12.2 to determine the maximum speed of the meteorite. (Sub-topic – P1.2)
▶️Answer/Explanation
The maximum speed of the meteorite is 36,000 m/s, as indicated by the highest point on the speed-time graph.
(c) The mass of the meteorite is 22,500 kg. The density of the meteorite is 7500 kg/m3.
(i) Calculate the volume of the meteorite. (Sub-topic – P1.4)
▶️Answer/Explanation
Using the formula: Volume = Mass ÷ Density,
Volume = 22,500 kg ÷ 7500 kg/m3 = 3.0 m3.
(ii) A scientist suggests that the meteorite contains metallic iron.
Suggest a simple way for the scientist to test for iron in an object found on Earth. (Sub-topic – C12.5)
▶️Answer/Explanation
The scientist can use a magnet to test for the presence of iron. If the object is attracted to the magnet, it likely contains iron.
(d) The meteorite’s temperature is 1500°C when it falls into the sea. The meteorite loses thermal energy to the water.
(i) State the main method of thermal energy transfer from the meteorite into the water. (Sub-topic – P2.3.1)
▶️Answer/Explanation
The main method of thermal energy transfer from the meteorite into the water is conduction, as the heat is transferred through direct contact between the meteorite and the water.
(ii) Some of the seawater evaporates.
Describe the process of evaporation in terms of the movement and energy of water molecules. (Sub-topic – P2.2.2)
▶️Answer/Explanation
Evaporation occurs when the most energetic water molecules at the surface gain enough energy to escape into the air as gas. This process cools the remaining liquid as the higher-energy molecules leave.
(iii) The meteorite is a solid and the seawater is a liquid.
Draw more circles in the boxes in Fig. 12.3 to show the arrangement and separation of particles in a solid and in a liquid. (Sub-topic – P2.1.1)
▶️Answer/Explanation
In a solid, particles are closely packed in a regular arrangement. In a liquid, particles are close together but not in a fixed arrangement, allowing them to move past each other.