Feb/March 2020

The table lists some measurable quantities. Which row states the correct order of magnitude for the measurable quantity in the unit given?

Physical quantities

The diagram depicts a particle $P$, moving with speed $v$, just before it collides with a particle $Q$ at rest and of the same mass. The collision is perfectly elastic. Which statement describes the motion of $P$ and of $Q$ immediately after the collision?

Linear momentum and its conservation

A particle sits within a uniform field, and the force on it points in the direction opposite to the field. What type of field is this, and what property of the particle does the field act on?

Electric current

A uniform rod with a weight of $20\,\text{N}$ and a length of $2.0\,\text{m}$ is subjected to two vertical forces, as illustrated. The forces indicated are $15\,\text{N}$ and $5.0\,\text{N}$. What are the resultant force acting on the rod and the resultant moment about the centre of gravity of the rod?

Turning effects of forces

A block is acted on by three coplanar forces. Which diagram shows the directions of the forces so that the block could be in equilibrium?

Equilibrium of forces

A gas occupies a volume of $0.012\,\text{m}^3$ in a cylinder at a pressure of $1.0 \times 10^5\,\text{Pa}$. $400\,\text{J}$ of work is done on the gas, while the pressure stays constant throughout. What is the gas’s final volume?

Energy conservation

A ball is launched straight up from the Earth’s surface. Which statement describes the ball’s energy as it moves higher through the air?

Gravitational potential energy and kinetic energy

A sledge with a mass of $50\,\text{kg}$ is resting on snow. It is dragged horizontally for $10\,\text{m}$ while opposing a friction force of $200\,\text{N}$, and then it is pulled horizontally over ice for another $10\,\text{m}$. The ice exerts no friction on the sledge. Next, it is raised vertically by $1\,\text{m}$ and, finally, it is taken back to its starting point at constant speed. In which part of the journey is the greatest amount of work done on the sledge?

Energy conservation

An object is transported in a vertical plane from X to Y, and then from Y to Z, as shown in the diagram. The distances between the different points are marked on the diagram. The lines XY and VZ are vertical. The object has a weight of $20\,\text{N}$. How much gravitational potential energy does the object gain when it moves from X to Z?

Gravitational potential energy and kinetic energy

A car moves up a slope at a steady speed of $25\,\text{m s}^{-1}$. The engine-driven wheels provide a forward force of $3000\,\text{N}$. Air resistance and friction together produce a total opposing force of $2100\,\text{N}$. The component of the car's weight acting down the slope is $900\,\text{N}$. Determine the rate at which thermal energy is dissipated.

Energy conservation

A composite rod is formed by joining a glass-reinforced plastic rod and a nylon rod end to end, as shown. Both rods have the same cross-sectional area, and each rod has a length of $1.00\,\text{m}$. The Young modulus $E_p$ of the plastic is $40\,\text{GPa}$ and the Young modulus $E_n$ of the nylon is $2.0\,\text{GPa}$. The composite rod breaks once its total extension reaches $3.0\,\text{mm}$. What is the maximum tensile stress that can be applied to the composite rod before it breaks?

Stress and strain

A byte (b) is made up of 8 bits. How many bits does 1 terabyte (1 Tb) contain?

SI units

The graph illustrates the non-linear force-extension relationship for a wire made of a new composite material. What is the most suitable estimate of the work done in stretching the wire to point P?

Elastic and plastic behaviour

A wave with frequency $15\,\text{Hz}$ moves through a medium at $24\,\text{m s}^{-1}$. What phase difference is there between two points separated by $2.0\,\text{m}$?

Progressive waves

Which row gives a description of a longitudinal wave and a medium through which it can travel?

Transverse and longitudinal waves

A sound wave appears on the screen of a cathode-ray oscilloscope, as shown. The time-base setting is $0.50\,\text{ms}$ per division. What is the frequency of the sound wave?

Progressive waves

An observer is positioned at the summit of a tall tower. An aeroplane that is emitting sound with a frequency of $1000\,\text{Hz}$ moves towards the observer at a speed of $165\,\text{m s}^{-1}$. The speed of sound is $330\,\text{m s}^{-1}$. What frequency does the observer receive for the sound?

Doppler effect for sound waves

How do the wavelengths of microwaves and X-rays compare in order of magnitude?

Electromagnetic spectrum

A musical instrument is constructed from a long tube with a mouthpiece at one end. The opposite end is open and flared, as illustrated. A musician produces stationary sound waves with a node at the mouthpiece and an antinode at the other end. The lowest frequency of sound that the instrument can produce is $92\,\text{Hz}$. Which other frequencies of sound can the instrument produce?

Stationary waves

A water wave travels through a gap in two barriers. The wavefronts then spread out, as shown. What is this phenomenon called?

Diffraction

The table lists four possible sets of values for the laser wavelength, slit separation and slit-screen distance in a two-slit interference experiment, to demonstrate the interference of visible light on a white screen. Which set will produce visible fringes?

Interference

Light with wavelength $\lambda$ strikes a diffraction grating at normal incidence, as illustrated. The angle between the two second-order maxima is $\varphi$. Which expression determines the spacing between the lines on the diffraction grating?

The diffraction grating

Which pair of quantities includes one scalar and one vector?

Scalars and vectors

An equilateral triangle has charges placed at its corners: two are positive and one is negative, and all three have the same magnitude. Which diagram shows the electric field around these charges?

Scalars and vectors

A negatively charged oil drop remains at rest, midway between two plates linked to a high voltage supply, as shown. Which alteration would not make the upward electrical force on the drop greater?

Potential difference and power

Electrons travel through a vacuum from one metal plate to a different metal plate. This produces an electric current of $48\,\mu\text{A}$ between the plates. How many electrons are released from the first plate in a time of $5.0$ minutes?

Electric current

As illustrated, a battery is connected to three resistors with resistances $12\,\Omega$, $6\,\Omega$ and $2\,\Omega$. The current supplied by the battery is $3\,\text{A}$. What is the value of the ratio $\dfrac{\text{power dissipated in the resistor of resistance } 6\,\Omega}{\text{power dissipated in the resistor of resistance } 2\,\Omega}$?

Potential difference and power

A manufacturer advises that, when an electric drill is used with a longer extension cord, the cord should have a larger cross-sectional area. What is one reason for this recommendation?

Resistance and resistivity

As shown, two batteries are joined together. Battery 1 has electromotive force (e.m.f.) $12\,\text{V}$ and internal resistance $0.3\,\Omega$. Battery 2 has e.m.f. $9\,\text{V}$ and internal resistance $0.1\,\Omega$. Determine the e.m.f. and the internal resistance of one battery that would produce the same effect as this arrangement.

Practical circuits

The diagram illustrates a circuit. What reading does the voltmeter show?

Practical circuits

For the circuits illustrated, the cell’s internal resistance is negligible. Which diagram illustrates a potential divider circuit that can change the potential difference (p.d.) across the lamp?

Potential dividers

Two alpha-particles that have the same kinetic energy travel towards a gold nucleus and are then deflected. Which diagram could represent the routes of the two alpha-particles?

Atoms, nuclei and radiation

The equation shows the decay of a nucleus $X$ into a nucleus $Y$. $^{A}_{Z}X \rightarrow {}^{A}_{Z-1}Y + p + q$. What particles are $p$ and $q$?

Atoms, nuclei and radiation

A transmitter sends out a pulse of electromagnetic waves towards a reflector. The pulse is then bounced back and arrives again at the transmitter. A detector is placed at the transmitter. The outgoing pulse and the returning pulse are shown on a cathode-ray oscilloscope (CRO), as illustrated. The pulse needs $6.3\,\mu\text{s}$ to move from the transmitter to the reflector. What is the CRO time-base setting?

Practical circuits

Which row shows the correct type and quark composition of the particle named?

Fundamental particles

A micrometer is being used to measure the diameters of two cylinders. Diameter of first cylinder $= (12.78 \pm 0.02)\,\text{mm}$. Diameter of second cylinder $= (16.24 \pm 0.03)\,\text{mm}$. The difference between the two diameters is then found. What is the uncertainty in this difference?

Errors and uncertainties

A stone is projected horizontally from the top of a cliff and lands in the sea beneath. Air resistance may be ignored. The stone’s trajectory is illustrated. In what direction does the resultant force on the stone act while it is falling?

Momentum and Newton's laws of motion

A car travels along a straight road with uniform acceleration. Oil drips from the car at a rate of one drop every two seconds. The diagram illustrates the separations between three consecutive oil drops on the road. The distances shown are $9.0\,\text{m}$ and $12.0\,\text{m}$. Determine the acceleration of the car.

Equations of motion

A person with mass $60\,\text{kg}$ is standing on accurate bathroom scales, set on the floor of an elevator (lift) in a tall building. At one particular moment, the bathroom scales show $58\,\text{kg}$. Which row could show the person’s direction of travel and the nature of the motion?

Non-uniform motion

The diagram presents graphs of different quantities plotted against time for an object released from a balloon that is stationary high in the atmosphere. Which statement could be correct?

Non-uniform motion

Length, mass and temperature are all SI base quantities. State two other SI base quantities.

Errors and uncertainties

The dolphin is moving underwater at a steady speed of $4.50\,\text{m s}^{-1}$.

Doppler effect for sound waves

State the meaning of work done.

Energy conservation

For a progressive wave, state what the term wavelength means.

The diffraction grating

Define the ohm in terms of V and A.

Resistance and resistivity

A uniform electric field is set up between two parallel metal plates. The electric field strength is $1.4 \times 10^{4}\,\text{N C}^{-1}$. The potential difference across the plates is $350\,\text{V}$.

Potential difference and power

State and explain whether a neutron is a fundamental particle.

Atoms, nuclei and radiation

Define gravitational potential at a point in space.

Gravitational potential

By reference to the photoelectric effect, explain what is meant by work function energy.

Photoelectric effect

Electrons are sped up by a potential difference of $100\,\text{kV}$. After striking a metal target, they slow down, and X-ray photons are produced.

Production and use of X-rays

Explain what the term binding energy of a nucleus means.

Mass defect and nuclear binding energy

A vessel with a volume of $85\,\text{m}^3$ contains $110\,\text{kg}$ of an ideal gas. At temperature $T$, the gas pressure is $1.0 \times 10^{5}\,\text{Pa}$. The mass of $1.0\,\text{mol}$ of this gas is $32\,\text{g}$.

Kinetic theory of gases

A body is moving in simple harmonic motion. Figure 3.1 shows how its velocity $v$ varies with displacement $x$.

Damped and forced oscillations, resonance

Explain why ultrasound used for medical diagnosis is sent out in pulses.

Production and use of ultrasound

State two advantages of sending data in digital form instead of analogue form.

Wave-particle duality

As shown in Fig. 6.1, two identical metal spheres A and B are both positively charged, and the distance between their centres is 24\,\text{cm}. Fig. 6.2 plots how the electric field strength E produced by the two spheres changes with distance x from the centre of A along the line joining the centres.

Electric field of a point charge

In Fig. 7.1, sketch the temperature characteristic of a negative temperature coefficient (n.t.c.) thermistor. Put the quantity and unit on each axis.

Electric potential

State what is meant by a magnetic field.

Force on a current-carrying conductor

The output from a power supply can be written as $V = 9.0 \sin 20t$, with $V$ denoting potential difference in volts and $t$ representing time in seconds.

Characteristics of alternating currents