OCR A Level Physics A Unified Physics June 2024 question paper H556/03

A flute is a musical instrument made from a long tube that is open at both ends.

A stationary sound wave in the tube produces a musical note.

The lowest frequency note that a standard flute produces in air is 262 Hz.

The speed of sound in air at a temperature of 20 °C is 340 m s^–1.

Show that a standard flute has an approximate length of 0.65 m.

In an ideal gas, the speed v of sound is given by

where

is a dimensionless constant that depends on the gas

R is the molar gas constant

T is the absolute temperature

M is the molar mass of the gas.

The table below shows values of and M for both air and helium.

Gas		M / g mol–1
Air	1.40	29.0
Helium	1.67	4.00

The kinetic model of an ideal gas assumes that there are a large number of particles in rapid, random motion.

State two further assumptions for the kinetic model of an ideal gas.

A standard flute is placed inside a sealed chamber.

The chamber is filled with helium at a temperature of –10 °C.

Calculate the lowest frequency that the flute could produce inside the chamber.

A group of students investigate the circuit shown in the figure below.

There are N capacitors, each of capacitance C, connected in parallel.

There are N resistors, each of resistance R, connected in series.

Initially, the students close the switch X. They then note the reading on the ammeter.

The students then open the switch. They record the time T for the reading on the ammeter to fall to half of its initial value.

The table below shows the students’ results.

Show that T = (ln 2)N²RC. (a)

The results table is repeated below.

Complete the last column for N = 1 and N = 2 in the table below.

The students begin to plot a graph of T (y-axis) against N² (x-axis). (d)

Draw a straight line of best fit on the graph.

Calculate the gradient of the straight line of best fit.

The value of C is known to be 1000 F ± 5%.

Use your gradient value from (iii) to find a value for R, in units of k , including an absolute uncertainty.

R =........ ±........ k

Following the investigation, the students discovered that the sixth 1000 F capacitor connected to the circuit was actually two 470 F capacitors connected in parallel.

State the type of error caused by this mistake.

Explain the effect that this error would have had on the calculated value of R.

A scientist uses a rocket to study the Earth’s atmosphere.

The scientist launches the rocket from rest at the point A at t = 0 seconds. The force produced by the rocket’s engine causes it to accelerate.

At t = 50 seconds, the rocket’s engine no longer produce an accelerating force as all of the fuel has been used. The rocket has reached point B. Its velocity is now 3.1 km s^–1 at an angle of 75° to the horizontal.

The rocket engine works by expelling hot gas backwards.

Explain, using Newton’s laws of motion, how the engine causes the rocket to accelerate between t = 0 and t = 50 s.

The length of an unloaded spring is approximately 4 cm.

The force constant k of the spring is 0.62 N cm^–1.

Describe how you could determine k using an appropriate experiment.

Calculate the magnitude of the block’s initial acceleration at the instant that the force F is removed.

Assume that the spring is not extended beyond its limit of proportionality.

acceleration =........ m s^–2

The block now moves with simple harmonic motion.

Calculate the frequency of this motion.

The block is replaced by a strong magnet L of slightly greater mass.

The oscillation frequency of this new arrangement is 2.5 Hz.

The magnet L is placed inside a coil X of insulated copper wire.

The coil X is connected with long wires to a second, identical coil Y.

A second strong magnet M is placed inside Y and attached to a vibration generator.

The vibration generator is then forced to oscillate with a frequency of approximately 2.5 Hz by

As magnet M oscillates, it moves in and out of coil Y.

........

The frequency of the vibration generator is now varied between 0.5 Hz and 5.0 Hz.

Suggest how the amplitude and frequency of the oscillations of L will change as the frequency of the generator is varied.

You may draw a diagram to support your answer.

Explain what is meant by

internal resistance of a cell

e.m.f. of a cell.

Suggest why the magnetic force acting on the proton has a different magnitude at X than at Y

At X, the motion of the proton is instantaneously equivalent to motion in a circle at a constant speed.

Calculate the radius of this circular motion.

1 Calculate the magnitude of the resultant force on the proton at Y.

2 Explain why the motion of the proton at Y is not instantaneously equivalent to motion in a circle at a constant speed.