OCR GCSE Physics B (21st Century) Paper 3 June 2019 question paper

Amir investigates melting ice.

He puts ice cubes on different materials. He then measures the time taken for each ice cube to completely melt.

Amir’s results are shown in the table.

Material	Time (min)
Metal foil	86
Paper	105
Carpet	162

(a)

Calculate the thermal energy needed to melt 20 g of ice.

The specific latent heat of melting for ice is 334 000 J / kg.

[3]

Answer

(b)

Explain why the ice cubes take different times to melt on different materials.

[2]

Answer

(c)

Amir discusses the experiment with Nina, another student.

(c)(i)

Suggest improvements to the experiment to solve each of these problems.

Amir’s problem........

Nina’s problem........

[2]

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(c)(ii)

Amir wants to speed up the experiment so it can be repeated more quickly.

Suggest one way he can change the experiment so that the ice melts more quickly, without making the experiment invalid.

[1]

Answer

Jamal is on a water slide.

(a)

Fig. 2.1 shows the force of gravity (weight) acting on Jamal.

(a)(i)

Add an arrow to Fig 2.1 to show the normal contact force between Jamal and the slide.

Label this arrow N.

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(a)(ii)

Add an arrow to Fig. 2.1 to show the force of friction between Jamal and the slide.

Label this arrow F.

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(b)(i)

State Newton’s third law.

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(b)(ii)

Explain how Newton’s third law applies to the force of gravity (weight) acting on Jamal.

[1]

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Beth works at a nuclear power station.

She is asked to investigate the risk caused by radioactive isotopes accidentally coming into contact with food.

(a)

Would swallowing this food be a contamination effect or an irradiation effect?

$Question 3, shown as an image$

Explain your answer.

[2]

Answer

(b)

Explain why it is hazardous if radioactive isotopes enter the body.

[1]

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(c)

Information about three isotopes is shown in the table.

Which isotope is most hazardous when inside the body?

Explain your answer.

[2]

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Kareem investigates the behaviour of a spring when it is loaded with masses and then unloaded.

He measures the extension of the spring each time he changes the load and plots his data onto the graph shown below.

(a)(i)

Explain how the data from the graph shows that the spring is non-linear.

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Answer

(a)(ii)

Suggest whether a non-linear spring could be used as a device to measure forces.

Justify your answer.

[1]

Answer

(b)(i)

Explain how the data on the graph shows plastic deformation.

[1]

Answer

(b)(ii)

Eve also looks at the data shown on the graph.

Suggest how to find out the force at which plastic deformation begins for this type of spring.

[2]

Answer

(c)

Kareem uses his spring to measure the weight of a metal block as 5.1 N.

Calculate the mass of the metal block.

Use the equation: weight = mass × gravitational field strength

Gravitational field strength = 10 N / kg

[2]

Answer

Thorium-232 is radioactive. It decays to an isotope of radium.

The graph in Fig. 5.1 shows how the number of neutrons and protons in the nucleus changes during this decay.

(a)

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(b)

State the type of radiation emitted during the decay shown in Fig. 5.1.

Give a reason for your answer.

Type of radiation........

Reason........

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(c)

The isotope of radium is also radioactive. It decays by emitting a beta particle.

Add an arrow to the graph in Fig. 5.1 to show this decay.

[1]

Answer

Kai is designing a head torch. The torch uses three small lamps.

The series circuit for Kai’s first design is shown in Circuit A.

(a)

The resistance of each bulb is 2800 maths symbol .

Calculate the current in Circuit A.

Give your answer to 2 significant figures.

[4]

Answer

(b)

Kai changes the circuit so that it now contains only one cell, but with the lamps wired together in parallel, as shown in Circuit B.

Circuit B

(b)(i)

Describe and explain how the brightness of the lamps in Circuit A compares to the brightness of the lamps in Circuit B.

[2]

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(b)(ii)

Justify which circuit is most suitable for use in the torch.

[1]

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Sarah experiments with magnets.

(a)(i)

Complete the diagram by drawing the pattern of magnetic field lines around the bar magnet.

[2]

Answer

(a)(ii)

Describe where the magnetic field is strongest, and how this is shown by the field lines.

[1]

Answer

(b)

Sarah makes a needle for a compass.

She repeatedly moves the needle across the bar magnet until it is magnetised. She then suspends the needle from a thread and it points north.

Explain whether the compass needle is a permanent or induced magnet.

[2]

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A solar flare is an explosion on the surface of the Sun.

Solar flares release huge amounts of radiation, including visible light and X-rays.

(a)

Describe two differences between visible light and X-rays.

[2]

Answer

(b)

Sometimes when there is a solar flare, a huge cloud of gas is also forced out from the Sun.

Jack finds out the following information:

Speed of X-rays in a vacuum 3.0 × 10⁸ m / s

• Typical wavelength of X-rays: 0.10 nm

• Time taken for visible light to travel from the Sun to the Earth: 8.3 minutes

• Speed of cloud of gas: 500 000 m / s

(b)(i)

Use the data to calculate the typical frequency of X-rays.

[3]

Answer

(b)(ii)

Calculate the time taken, in minutes, for the cloud of gas to reach the Earth.

Time taken =........ minutes

[4]

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Jane investigates the maximum power provided by two types of solar cell, as shown in Fig. 9.1 The solar cells are not the same size.

Cell X
Cell Y

Jane uses the circuit shown in Fig. 9.2 to measure the power provided by each cell. She carefully controls the intensity of light falling on each solar cell so that it does not change.

(a)

Describe how to use the circuit in Fig. 9.2 to measure the maximum power provided by each cell.

Include details of any calculations that must be completed.

[3]

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(b)

The table shows the results of Jane’s experiment.

Compare the effectiveness of solar cells X and Y, taking into account their surface area.

[3]

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(c)

Suggest two factors, other than maximum power, that could affect someone’s decision to use solar cells to generate electricity for their home.

[2]

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Amaya and Li are clowns in a circus. They are preparing a new show.

In the show, a water balloon will be dropped on Li’s head from different heights. Amaya lifts the water balloon to a height 5.0 m above Li’s head using a pulley.

(a)

Describe all the changes in the way energy is stored, starting from before Amaya starts to lift the water balloon, and finishing after the water balloon has hit Li.

In your answer you should clearly state what is happening to the water balloon as the energy is transferred between each of the stores.

[3]

Answer

(b)

The mass of the water balloon is 1.6 kg.

(b)(i)

Calculate the minimum work that must be done by Amaya to lift the water balloon a height of 5.0 m.

Gravitational field strength = 10 N / kg

[2]

Answer

(b)(ii)

Use your answer to (b)(i) to calculate the maximum possible speed of the water balloon when it hits Li.

Speed =........ m / s

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Kepler-445d is a planet orbiting a distant star in our galaxy. It was discovered in 2015.

Astronomers believe that Kepler-445d is similar to the Earth. However, it orbits a star that emits light with a longer principal wavelength than the Sun.

(a)

State how the surface temperature of the star compares to the surface temperature of the Sun.

[1]

Answer

(b)

The intensity of radiation emitted by the star is much lower than that emitted by the Sun. However, the surface temperature of Kepler-445d is thought to be similar to the surface temperature of the Earth.

Give two possible reasons to explain how Kepler-445d could be at a similar temperature to Earth.

[2]

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