OCR A Level Physics A Modelling Physics November 2020 question paper H556/01

An athlete is running at a speed of about 5 m s^–1.

What is a reasonable estimate for the kinetic energy of this athlete?

A 12 J

B 100 J

C 900 J

D 800 000 J

Your answer

Which pair of quantities have the same S.I. base units?

A force, strain

B force, stress

C pressure, stress

D strain, upthrust

Your answer

A tennis ball is hit with a racket. The force applied by the racket on the ball is F. The ball has a vertical path through the air.

Which statement is correct when the ball is at its maximum height?

A The ball has a downward acceleration.

B The force acting on the ball is F.

C The ball experiences greatest drag.

D The weight of the ball is equal to the drag.

Your answer

An oscillator is forced to oscillate at different frequencies. The graph of amplitude A against driving frequency f for this oscillator is shown.

The damping on the oscillator is now decreased.

Which of the following statements is/are correct?

1 The amplitude of the oscillations at any frequency decreases. 2 The maximum amplitude occurs at a lower frequency. 3 The peak on the graph becomes thinner.

A Only 1

B Only 2

C Only 3

D 1, 2 and 3

Your answer

The gravitational force between two point-mass objects X and Y is F₁.

The mass of X increases and the distance between X and Y is halved.

Which statement about the new gravitational force F₂ between these two objects is correct?

A 0 < F₂ < 0.25F₁

B F₂ > 4F₁

C F₂ = F₁

D 2F₁ < F₂ < 4F₁

Your answer

The diagram below shows two energy levels for the electron in the hydrogen atom.

The electron makes the transition shown by the arrow.

What is the wavelength of the photon emitted?

A 293 nm

B 366 nm

C 488 nm

D 1460 nm

Your answer

A wooden block is stationary on a ramp.

The diagram is not drawn to scale.

The block has weight W. The normal contact force on the block is N. The frictional force F on the block is not shown on the diagram.

Which triangle of forces diagram is correct?

Your answer

Laser light of wavelength of 640 nm is incident normally at a diffraction grating. The separation between adjacent lines (slits) is 3.3 × 10^–6 m.

What is the total number of bright spots that can be observed in the diffraction pattern?

A 5

B 6

C 10

D 11

Your answer

A spring is stretched by hanging on it a variable mass m. The mass m is always at rest. The spring obeys Hooke’s law.

What is the relationship between the elastic potential energy E in the spring and the mass m ?

A E m^–1

B E m^–2

C E m

D E m²

Your answer

An oscillator is executing simple harmonic motion.

Which graph of kinetic energy KE against displacement x is correct for this oscillator?

Your answer

The velocity v against time t graphs for four objects A, B, C and D are shown below.

Which object travels the greatest distance between t = 0 and t = T ?

Your answer

The kinetic theory of matter is a model used to describe the behaviour of particles (atoms or molecules) in an ideal gas. There are a number of assumptions made in the kinetic model for an ideal gas.

Which one of the following assumptions is not correct?

A The collisions of particles with each other and the container walls are perfectly inelastic.

B The electrostatic forces between particles are negligible except during collisions.

C The particles occupy negligible volume compared to the volume of the gas.

D There are a large number of particles in random motion.

Your answer

A truck pulls a car up a slope at a constant speed. The truck and the car are joined with a steel tow bar, as shown in the diagram.

The diagram is not drawn to scale.

The slope is 10 to the horizontal ground. The mass of the car is 1100 kg. The car travels from A to B. The vertical distance between A and B is 120 m.

There are four forces acting on the car travelling up the slope.

Complete the free-body diagram below for the car and label the missing forces.

Show that the component of the weight of the car W_s acting down the slope is about 1900 N.

The total frictional force acting on the car as it travels up the slope is 300 N.

Calculate the force provided by the tow bar on the car.

The steel tow bar used to pull the car has length 0.50 m and diameter 1.2 × 10^–2 m. (e) The Young modulus of steel is 2.0 × 10¹¹ Pa.

Calculate the extension x of the tow bar as the car travels up the slope.

A heater is used to heat water in a beaker.

Before switching on, the metal heater and the water are both at room temperature.

Describe the motion of the atoms of the metal heater and of the water molecules.

* A student is carrying out an experiment to determine the specific latent heat of fusion L_f of ice. The student has two sets of apparatus next to each other on the laboratory bench, as shown in Fig. 17.1 and Fig. 17.2.

Both funnels are identical and have the same mass of crushed ice at 0 C.

The current in the heater is 5.0 A and the potential difference across it is 12 V.

Fig. 17.3 shows the variation of mass of water m collected in each beaker with time t.

Describe and explain the shape of the two graphs in Fig. 17.3 and use them to determine the

specific latent heat of fusion L_f of ice.

Additional answer space if required

An archer fires an arrow towards a target as shown below.

The diagram is not drawn to scale.

The centre of the target is at the same height as the initial position of the arrow. The target is a distance of 90 m from the arrow. The arrow has an initial velocity of 68 m s^–1 and is fired at an angle of 11 to the horizontal.

Air resistance has negligible effect on the motion of the arrow.

Describe how the kinetic energy of the arrow changes during its journey from when it is fired until it reaches its maximum height.

Show that the time taken for the arrow to reach its maximum height is about 1.3 s.

The arrow misses the target.

Calculate the horizontal distance, measured along the base line, by which the arrow misses the target.

Explain what is meant by an inelastic collision.

The target is mounted on wheels. The target has a much larger mass than the mass of the arrow.

Using ideas of momentum, explain the velocity of the target immediately after the arrow sticks into the target.

19* A student makes a pendulum using a length of string with a ball of adhesive putty which acts as a bob. The mass of this bob is M. A similar second pendulum is constructed with the same length of string but with a bob of a smaller mass. The mass of this bob is m.

The arrangement of the pendulums is shown below.

The bob of mass M is pulled back to a vertical height of H from its rest position. It is released and collides with the bob of mass m. The two bobs then stick together and reach a maximum vertical height h from the rest position.

Describe how to perform an experiment to test the validity of this equation and how the data can

be analysed.

Additional answer space if required

A small object of mass m is placed on a rotating horizontal metal disc at a distance r from the centre of the disc.

The frequency of rotation is adjusted using a motor attached to the disc.

The frequency of rotation of the disc is slowly increased from zero, until the object slips off. At this point, the friction F acting on the object is equal to the centripetal force.

The friction F is given by the expression F = kmg, where k is a constant and g is the acceleration of free fall. The constant k has no units.

A kiln used to harden ceramics is shown below.

The internal chamber is a cube. Each side of this cube has length 0.46 m. The chamber is sealed and full of argon. Argon behaves as an ideal gas.

The kiln is initially at 20 C. The argon in the kiln has an initial pressure of 100 kPa.

Calculate the amount of argon n in the chamber in moles.

The temperature of the kiln is increased from 20 C to 1300 C.

Calculate the pressure in kPa at 1300 C.

The temperature of the kiln is 1300 C. A single atom of argon is travelling horizontally towards the vertical side X of the chamber. The initial speed of this atom is 990 m s^–1. After collision, it rebounds at the same speed.

Calculate the change in momentum p of this atom.

• mass of argon atom = 6.6 × 10^–26 kg

=........ kg m s^–1 p

Assume that this atom does not collide with any other argon atoms inside the chamber. Instead, it travels horizontally, making repeated collisions with the opposite vertical walls of the chamber.

1 Show that the atom makes about 1000 collisions with side X in a time interval of 1.0 s.

2 Calculate the average force F on side X made by the atom.

Without calculation, explain how your answer to (ii)2 could be used to estimate the total pressure exerted by the atoms of the argon gas in the kiln.

A long wooden cylinder is placed into a liquid and it floats as shown.

The length of the cylinder below the liquid level is 15 cm.

State Archimedes’ principle.

The pressure exerted by the liquid alone on the bottom of the cylinder is 1.9 × 10³ Pa. (ii)

Calculate the density ρ of the liquid.

=........ kg m^–3

The cylinder is pushed down into the liquid and then allowed to oscillate freely. The graph of displacement x against time t is shown below.

The cylinder oscillates with simple harmonic motion with frequency of 1.4 Hz.

Calculate the displacement, in cm, at time t = 0.60 s.

Calculate the maximum speed of the oscillating cylinder.

maximum speed =........ m s^–1

The cylinder is now pushed down further into the liquid before being released. As before, the cylinder oscillates with simple harmonic motion.

State the effect this has on

1 the amplitude

2 the period.

In June 2018, the spacecraft Hayabusa2 arrived at an asteroid called Ryugu.

The asteroid orbits the Sun in an elliptical orbit as shown below.

The diagram is not drawn to scale.

Indicate with a letter X on the orbit where the asteroid would be moving at maximum

speed.

Use Kepler’s second law to explain your answer to (a)(i).

Define gravitational potential.

Show that the magnitude of the gradient of the graph is equal to GM, where M is the mass of the asteroid and G is the gravitational constant.

Use the gradient of the graph to show that the mass M of the asteroid is about 4.6 × 10¹¹ kg.

Our Sun will eventually become a red giant.

Describe and explain the next stages of evolution of our Sun.

Rigel is a blue giant star in the constellation of Orion. The table below shows some data about Rigel and about our Sun.

Show that the surface temperature of Rigel is 12 000 K.

Calculate the radius of Rigel.

An astronomer claims to have discovered a white dwarf with a mass twice that of our Sun.

Suggest why this claim must be incorrect.