OCR GCSE Physics B (21st Century) Paper 4 June 2019 question paper

This question is about gears and levers.

A wristwatch with its back cover removed is shown in Fig. 1.1.

You can see some of the gears inside the wristwatch.

Two gears Q and R are shown in Fig. 1.2.

The gear Q has 40 teeth and gear R has 20 teeth. Both gears have the same size teeth.

The gear Q moves in a clockwise direction.

Gear Q rotates at 6 revolutions per minute.

On Fig. 1.2, show the direction of rotation of gear R.

How many revolutions are completed by gear R in one minute?

Number of revolutions =........ per minute

The lid of a can of paint has a lip which makes it easier to open, using a lever.

The diagram below shows a screwdriver placed under the lip.

In an experiment, masses are added to the mass hanger to open the lid.

The mass hanger hangs at a distance of 0.20 m from the rim (pivot) of the can.

A total weight of 32 N of the hanging masses opens the lid.

Calculate the moment of this force.

Use Fig. 3.2 to explain how the light intensity affects the resistance of the LDR.

The LDR is connected to a cell, an ammeter and a voltmeter.

The meter readings from the ammeter and voltmeter are used to determine the resistance of the LDR.

Complete Fig. 3.3 to show the likely circuit connected by Lyla and Alex.

Lyla and Alex worked in different parts of the laboratory to conduct their investigations.

Both used identical sheets of tracing paper and identical LDRs but their results were different.

Suggest one thing that must be kept the same to get identical results.

Suggest one improvement that needs to be made to get identical results.

Marshmallows are spongy sweets that have tiny pockets of trapped air. Ling is using marshmallows to investigate the relationship between pressure and volume.

Ling places a small marshmallow inside an air-filled plastic syringe. The open end of the syringe is blocked. The syringe has a millilitre (ml) scale.

The volume of the air inside the syringe is increased by moving the plunger to the left.

The temperature of the air inside the syringe remains constant.

Explain why the marshmallow increases in size when the volume of air inside the syringe is increased.

Ling makes the following hypothesis.

Ling

Explain how Ling can take measurements, and analyse the data to check her hypothesis.

Ultrasound is used in hospitals to image the inside of our bodies.

Fig. 5.1 shows an ultrasound wave travelling from air into the patient’s skin.

The ultrasound wave is refracted at the air-skin boundary.

Describe what happens to the speed, frequency and wavelength of the ultrasound wave as it travels from air to skin.

Speed:........

Frequency:........

Wavelength:........

Fig. 5.2 is a diagram of a human eye. Ultrasound can be used to determine the length of an eyeball.

Pulses of ultrasound are sent into the eye.

The ultrasound pulse is reflected at the retina.

It takes 4.0 × 10^–5 s for an ultrasound pulse to travel from the front of the eye, to the retina, and then back to the front of the eye.

The speed of the ultrasound pulse in the eye is 1100 m / s.

Calculate the length of the eyeball in metres.

Fig. 5.3 shows the ultrasound pulses that were sent into the eye, as described in part (b)

Suggest an explanation for the other two pulses ringed in the diagram.

Kareem is researching replacement bulbs for his grandad.

He finds three types of bulbs – incandescent, compact fluorescent light (CFL) and light-emitting diode (LED).

Table 6.1 shows some information on these bulbs.

The three bulbs in Table 6.1 have the same brightness.

Calculate the number of incandescent bulbs that would be required to do the same job as a single LED bulb, in 50 000 hours.

Use information from Table 6.1.

Calculate the total cost, in pence, of using one LED bulb for its lifetime.

The cost of one kWh of energy is 13 p.

Use information from Table 6.1.

Eve is investigating the force on a current-carrying wire when it is placed in a magnetic field, as shown in Fig. 7.1.

The direction of the current in the wire is from left to right.

The magnetic field of the magnet is in the plane of the paper and perpendicular to the current-carrying wire.

The current-carrying wire moves.

Use Fleming’s left-hand rule to predict the direction in which the wire moves.

Tick (✓) one box.

Describe how you used Fleming’s left-hand rule to find the direction in which the wire moves.

Explain why the current-carrying wire moves.

Use ideas about magnetic fields in your answer.

The current in the wire is 2.0 A. The magnetic flux density is 0.060 T.

Calculate the force acting on the 4.5 cm length of the wire.

Explain what happens to the size of the force in (c) when the current in the wire is doubled.

8* Electrical energy is transported across the country using the National Grid.

Transformers play a key role in this transportation.

Describe and explain the role of transformers in the transmission of electrical power from power stations to our homes.

You may include a labelled diagram of a transformer.

Astronomers use telescopes in space to observe the Universe.

The Kepler telescope has been used to detect planets around distant stars.

It orbits around the Sun in a circular orbit, as shown in Fig. 9.1.

Ben makes the following comment.

Is Ben correct?

Explain your answer.

The Hubble Space Telescope discovered the Baby Boom Galaxy, where one star is formed every two hours.

Explain how a star is initially formed.

Use ideas from the particle model in your answer.

Explain the evidence for the ‘Big Bang’ model of the Universe.

The Hubble Space Telescope was launched from the surface of the Earth using a reusable rocket (Space Shuttle).

Fig. 9.2 shows the typical forces acting on a rocket during lift-off.

3.1 × 10⁷N Upward Force (thrust) on rocket

Total weight of rocket 2.0 × 10⁷N

Fig. 9.2

The total mass of the rocket is 2.0 × 10⁶ kg.

Calculate the acceleration of the rocket during lift-off.

Acceleration =........ m / s²

A delivery company uses GPS tracker devices to monitor the velocity of their vans.

Calculate the acceleration of the van in section C.

Acceleration =........ m / s²

One of the vans collides with a stationary car.

Fig. 10.2 shows the momentum against time graph for the van.

Use Fig. 10.2 to explain why the momentum of the car is 6000 kg m / s immediately after the collision.

The mass of the van is 1500 kg and the mass of the car is 1000 kg.

Calculate the speed of the car immediately after the collision.

Use the information given in (b)(i) to help you answer the question.

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

A patient has been diagnosed with a very small cancerous growth on her neck.

A doctor gives the patient a leaflet with information on two possible treatments for her cancer: X-ray radiotherapy and brachytherapy. The information is shown in the table.

The patient and her doctor decide to treat the cancer with radiotherapy.

Why did they decide to treat the cancer with radiotherapy?

Use information from the table in your answer.

Radioactive iridium-192 is used for the brachytherapy treatment.

The half-life of iridium-192 is 74 days.

The initial activity of the iridium source is 2.0 × 10⁷ counts per second.

Sketch a graph to show how the activity of the source changes with time.

The initial activity of another iridium-192 source is different from (b)(i).

What fraction of the iridium nuclei are left in the new source after 3 half-lives?

Iridium-192 is a low-level waste product of fission reactions in a nuclear power station.

Low-level wastes, such as Iridium-192, have short half-lives.

Amaya and James are discussing what should happen with low-level wastes like iridium.

Who do you agree with? Justify your answer.