May/June 2021

What would be a sensible estimate for the volume of an adult person?

Density and pressure

Which quantities remain conserved during an inelastic collision?

Linear momentum and its conservation

A charged oil drop remains at rest between two charged parallel plates. Which forces are exerted on the oil drop?

Equilibrium of forces

Which pair of forces produces a couple with a torque of $30\,\text{N m}$?

Turning effects of forces

A rigid uniform bar XZ with negligible mass has a length of 1.20 m. The bar is mounted on a pivot at point P. As shown, three coplanar forces act on the bar. Forces of $16\,\text{N}$ and $20\,\text{N}$ are applied perpendicularly to the bar at points X and Y respectively. Force $F$ is applied at point Z at an angle of $30^\circ$ to the axis of the bar. The positions of the pivot and the forces along the bar are shown. The bar has a resultant moment about P of $6.0\,\text{N m}$ clockwise. What is the magnitude of $F$?

Turning effects of forces

A layer of water with depth $9.0\,\text{cm}$ has a layer of oil with depth $5.0\,\text{cm}$ above it in a measuring cylinder. The density of the water is $1000\,\text{kg m}^{-3}$ and the density of the oil is $800\,\text{kg m}^{-3}$. What total pressure is exerted on the base of the measuring cylinder by the oil and the water?

Density and pressure

A rocket is launched vertically. As it increases speed upward after leaving the launch pad, which energy stores are changing?

Gravitational potential energy and kinetic energy

To unwrap a tape roll with a length of $50\,\text{m}$, a steady force of $20\,\text{N}$ is needed. How much work is done in unwrapping the entire roll?

Energy conservation

A trolley with mass $600\,\text{kg}$ starts at point P on a slope, with its position $80\,\text{m}$ above ground level, as shown. It is let go from rest and travels down the slope, finally stopping at point Q, which is at height $h$ above ground level. The distance travelled by the trolley along the slope from P to Q is $1.5\,\text{km}$. A steady resistive force of $300\,\text{N}$ acts against the trolley’s motion on the slope. Find $h$.

Energy conservation

A body with a weight of $15.0\,\text{N}$ is dragged across a horizontal surface at a steady speed of $2.00\,\text{m s}^{-1}$. The pulling force on the body is $12.0\,\text{N}$ at an angle of $30.0^\circ$ to the horizontal, as illustrated. What is the power used to move the body?

Energy conservation

The spring constants of four springs are obtained by plotting the graphs below of force $F$ against extension $x$. Which sequence of graphs shows the spring constants in decreasing order?

Elastic and plastic behaviour

Which unit combination could be used to express the power dissipated in a resistor?

Potential difference and power

A rod is stretched by forces acting at its two ends, causing it to lengthen. The graph shows how the rod’s extension $e$ varies with force $F$. Point P marks the elastic limit. Which shaded region shows the work done during the plastic deformation of the rod?

Elastic and plastic behaviour

Sources at points P and Q generate two identical waves. These waves follow different routes to arrive at point R, as illustrated. Each wave has a wavelength of $6.0\,\text{cm}$. At point R, the waves are in phase. What phase difference is there between the waves as they leave points P and Q?

Interference

A longitudinal wave moves from left to right, and the oscillations are parallel to the direction in which the wave transfers energy. This wave may be shown on a graph of how the particles’ displacement from their equilibrium positions varies with distance at a single moment. Which point on the graph marks the centre of a compression?

Transverse and longitudinal waves

A stationary wave is produced by two identical sound waves. A microphone is placed where the loudness is at a maximum. It is then shifted along the stationary wave from this first maximum-loudness position to the fourth maximum-loudness position. The microphone travels a distance of $12\,\text{cm}$. The speed of sound is $330\,\text{m s}^{-1}$. What is the frequency of the sound waves?

Stationary waves

An ambulance has a siren that produces sound at a fixed frequency. The ambulance is travelling straight towards a stationary observer. As the ambulance gets closer to the observer, it slows down, and after it has gone past the observer, it speeds up. How does the frequency of the sound heard by the observer change while the ambulance is approaching and while it is moving away from the observer?

Doppler effect for sound waves

Microwaves travelling in a vacuum move at speed $X$ and have wavelength of order of magnitude $Y$. What are the speed and one possible order of magnitude of wavelength of X-rays in a vacuum?

Electromagnetic spectrum

The diagram illustrates a section of a stationary wave on a string. X and Y are positions on the string. The vibrations at X and Y are $180^\circ$ out of phase. What is the separation between X and Y?

Stationary waves

What wave behaviour does the diagram show?

Interference

A teacher arranges the apparatus shown to show a double-slit interference pattern on a screen. Which alteration to the apparatus would make the fringe spacing larger?

Interference

A single wavelength of light that is unknown, together with blue light of one wavelength, is each directed normally at a diffraction grating. This gives two separate diffraction patterns, one corresponding to each wavelength. For the blue light, the third-order maximum is observed at the same angle as the second-order maximum for the unknown light. The wavelength of the blue light is $480\,\text{nm}$. What is the wavelength of the unknown light?

The diffraction grating

A force of $10\,\text{N}$ together with a force of $5\,\text{N}$ act on an object. The angle between these two forces is $150^\circ$. The resultant force on the object may be broken down into two perpendicular components. Which row gives numerical expressions for one possible pair of perpendicular components?

Scalars and vectors

Determine the electric field strength in a region in which a proton accelerates at $2.00\,\text{m s}^{-2}$ because of the field.

Electric current

An oil drop with mass $2.6 \times 10^{-15}\,\text{kg}$ and charge $-4.8 \times 10^{-19}\,\text{C}$ is situated in a vacuum between two horizontal plates. The plates are separated by $2.0\,\text{cm}$ and there is a potential difference (p.d.) of $1200\,\text{V}$ between them, as shown. Which statement best describes the motion of the oil drop?

Potential difference and power

Which two units are combined to define the coulomb?

Electric current

A mobile phone battery is connected to a constant potential difference of $5.0\,\text{V}$ for charging. Over a time of $1.0\,\text{hour}$, the initial current of $0.50\,\text{A}$ gradually falls to zero, as shown. What is the best estimate of the energy transferred to the battery during the $2.0\,\text{hours}$ represented on the graph?

Potential difference and power

A wire is placed in an electric circuit, and the current in the wire is measured. Which single change could increase the current in the wire?

Resistance and resistivity

A cell is said to have an electromotive force (e.m.f.) of $6\,\text{V}$. What is meant by this?

Potential difference and power

The diagram depicts a resistor network. Every resistor has resistance $R$. What is the overall resistance of the network between points X and Y?

Resistance and resistivity

As shown, three resistors are arranged in series with a battery. The battery is assumed to have negligible internal resistance. What potential difference is across the $180\,\Omega$ resistor?

Potential dividers

A potentiometer circuit is being used to find the unknown electromotive force (e.m.f.) of a cell X. In the circuit diagram, E is a cell whose e.m.f. is known precisely. QR is the potentiometer wire, and it has a movable contact S. Contact S is linked to a galvanometer and to cell X. Which requirement is not essential for determining the e.m.f. of X from this circuit?

Practical circuits

A uranium nucleus, $^{235}_{92}\text{U}$, goes through a chain of decays. Over the course of the decay sequence, two $\alpha$-particles and one $\beta^-$ particle are released. This produces a nucleus of actinium, Ac. What is the correct notation for the actinium nuclide that is produced?

Atoms, nuclei and radiation

A signal with frequency $25\,\text{Hz}$ is shown on the screen of a cathode-ray oscilloscope. What time-base setting is needed?

Practical circuits

Which particle counts as a fundamental particle?

Fundamental particles

A micrometer screw gauge is employed to find the diameter of a wire. When the jaws are shut, the micrometer gives a reading of $(-0.05 \pm 0.02)\,\text{mm}$. With the wire placed between the two jaws, the reading becomes $(+1.03 \pm 0.02)\,\text{mm}$. Determine the diameter of the wire.

Errors and uncertainties

A projectile is fired at an angle above the horizontal at time $t = 0$. It moves over level ground, as illustrated. Air resistance is negligible. Which graph best represents how the speed of the projectile changes with $t$ from launch until it reaches the ground?

Equations of motion

A train, which begins from rest at a station, accelerates uniformly at $0.20\,\text{m s}^{-2}$ until its speed reaches $20\,\text{m s}^{-1}$. It then continues for a period at constant speed and afterwards decelerates uniformly at $0.40\,\text{m s}^{-2}$ until it is brought to rest at the next station. The separation between the two stations is $3000\,\text{m}$. What is the time taken by the train to travel between the two stations?

Equations of motion

A rocket is launched from the Earth into space. Newton’s third law of motion explains that forces occur in pairs. One force in this pair is the weight of the rocket. What is the other force in this pair?

Momentum and Newton's laws of motion

The graph illustrates the way quantity $P$ changes with quantity $Q$ for a body falling straight down in a uniform gravitational field with air resistance. Which pair of quantities could $P$ and $Q$ stand for?

Non-uniform motion

Which of the following is not a reasonable estimate for the physical property shown?

Physical quantities

One nitrogen molecule $P$, moving at a speed of $320\,\text{m s}^{-1}$ in a vacuum, collides with a nitrogen molecule $Q$ that is at rest. Following the collision, $P$ moves with a velocity of $180\,\text{m s}^{-1}$ at an angle of $55^{\circ}$ to its original direction. $Q$ moves in a direction making an angle of $34^{\circ}$ with the initial direction of $P$. Assume that no external forces act on the molecules. What is the magnitude $v$ of the velocity of $Q$ after the collision?

Linear momentum and its conservation

A charged particle is situated in a uniform force field. The force acting on the particle points in the opposite direction to the field. Identify the field and the charge on the particle.

Electric current

A disc with radius $r$ is subjected to two equal forces of magnitude $F$ that act in opposite directions. These forces create a couple, as illustrated. What is the torque of this couple?

Turning effects of forces

A square sign of uniform weight $40\,\text{N}$ is hung vertically from its top edge by a horizontal hinge, as illustrated. The hinge is not frictionless. If an external force moves the sign away from the vertical and it is then let go, it does not return to the vertical position. The greatest torque exerted by the hinge on the sign is $6.0\,\text{N m}$. The sign is turned through $90^{\circ}$ so that it is horizontal and is then slowly released. At what angle to the vertical does the sign remain after release?

Turning effects of forces

The cross-section of each elephant foot is circular, and its circumference is $1.4\,\text{m}$. The elephant’s mass is $5400\,\text{kg}$. The elephant is motionless, with all four feet touching the ground. Take the pressure beneath each foot to be equal. What is the approximate pressure exerted on the ground by one of the elephant’s feet?

Density and pressure

A stone is descending vertically through the air at a steady (terminal) velocity. Which change in energy is taking place?

Energy conservation

An object with weight $12\,\text{N}$ is at rest on a platform at the top of a container fitted with two pistons, as illustrated. The container holds a fixed mass of gas, and the pistons can move freely. The plunger is then pressed slowly $4.0\,\text{cm}$ to the right. Consequently, the object rises slowly by $0.50\,\text{cm}$. What is the amount of work done on the object?

Energy conservation

A constant force $F$ is applied to a car of mass $m$, causing it to travel up a slope over a distance $s$ at constant velocity $v$. The angle of the slope to the horizontal is $\alpha$. The acceleration of free fall is $g$. Find the ratio $\frac{\text{gravitational potential energy gained by car}}{\text{work done by force }F}$?

Gravitational potential energy and kinetic energy

What does the term power mean?

Potential difference and power

As illustrated, a steel bar with a circular cross-section is being pulled by tension $T$. The diameter of the wider section is twice the diameter of the narrower section. Determine the value of $\frac{\text{stress in the wide portion}}{\text{stress in the narrow portion}}$?

Stress and strain

Which quantity might be expressed in units of $\text{N m V}^{-1}$?

SI units

Two guitar strings are subjected to tensile forces. String X experiences a tensile force $F$, producing an extension $x$. String Y experiences a tensile force $2F$, producing an extension $2x$. The strings follow Hooke’s law. What is the ratio $\frac{\text{strain energy in stretched string X}}{\text{strain energy in stretched string Y}}$?

Stress and strain

Two lasers produce light in a vacuum. One laser gives out red light, while the other gives out green light. Which property of the light from the two lasers must be different?

Electromagnetic spectrum

In a progressive wave, two particles are separated by $10\,\text{cm}$. The two graphs illustrate how the displacement $d$ of each particle changes with time $t$. What situation could the two graphs represent?

Progressive waves

A microphone, linked to a cathode-ray oscilloscope (CRO), detects a sound wave. The CRO screen shows a waveform, as illustrated. The time-base is adjusted to $20\,\mu\text{s div}^{-1}$. What is the frequency of the sound wave?

Progressive waves

A person is standing beside a straight railway line. A train travels towards the person and sound is produced by its whistle. As the train comes nearer, the person hears a sound with frequency $1690\,\text{Hz}$. When the train has passed and is moving away, the person hears a sound with frequency $1500\,\text{Hz}$. The speed of sound in air is $340\,\text{m s}^{-1}$. Determine the speed of the train.

Doppler effect for sound waves

Which list arranges electromagnetic waves in order of decreasing frequency?

Electromagnetic spectrum

A pipe with length $L$ has one end open and the other end closed. A loudspeaker placed at the open end sends a sound wave into the pipe. Once a stationary wave is established, the open end of the pipe is an antinode. Which wavelength of sound could be used to create a stationary wave?

Stationary waves

Which diagram most accurately illustrates how water waves diffract as they move through a gap in a barrier?

Diffraction

In a two-source interference experiment, light with a single frequency falls on a double slit. The light waves emerging from the slits are coherent. What does coherent mean?

Interference

A collimated beam of light contains radiation with wavelength $420\,\text{nm}$ and radiation with wavelength $630\,\text{nm}$. It is incident normally on a diffraction grating. The diffraction maxima from the two wavelengths coincide only at an angle of $31^{\circ}$ to the direction of the incident light beam. What could the line spacing of the diffraction grating be?

The diffraction grating

A body is subject to two forces: $10\ \text{N}$ vertically and $6\ \text{N}$ at $40^\circ$ to the vertical, as illustrated. What is the resultant force on the body?

Scalars and vectors

A positively charged particle P is placed in an electric field, as illustrated. The field lines (lines of force) are parallel and equally spaced. Which statement is correct?

Potential difference and power

The diagram illustrates two parallel metal plates P and Q, which are spaced $5.0\,\text{mm}$ apart. The potential difference between the plates is $700\,\text{V}$. Plate Q is earthed. What are the magnitude and direction of the electric field at point R?

Potential difference and power

A metal conductor with a wedge shape, of length $L$, non-uniform width and constant thickness, is attached to a cell, as illustrated. Which graph most accurately indicates how the mean drift velocity $v$ of electrons in the conductor changes with distance $x$ from end X?

Electric current

An electrical supply has a power output of $2.4\,\text{kW}$ when the potential difference (p.d.) is $240\,\text{V}$. The two wires linking the supply to a kettle each have a resistance of $0.50\,\Omega$, as shown. What power is delivered to the kettle, and what is the p.d. across the kettle?

Practical circuits

The graph illustrates how current $I$ varies with potential difference $V$ for components X, Y and Z. Which row correctly identifies the components?

Resistance and resistivity

A wire has a resistance of $9.55\,\Omega$ and a diameter of $0.280\,\text{mm}$. The wire is made from a metal with resistivity $4.90 \times 10^{-7}\,\Omega\,\text{m}$. What length is the wire?

Resistance and resistivity

A cell with a constant electromotive force (e.m.f.) and internal resistance is joined to a fixed resistor $R$ by means of a potentiometer. A voltmeter is used to measure the potential difference (p.d.) across the terminals of the cell. Which statement accounts for how the voltmeter reading changes as contact Z is moved closer to end X of the potentiometer?

Potential dividers

A cell with electromotive force (e.m.f.) $E$ and negligible internal resistance is connected into a circuit. As shown, the circuit includes currents $I_1$, $I_2$ and $I_3$, as well as potential differences $V_1$, $V_2$ and $V_3$. Which equation states Kirchhoff's first law?

Kirchhoff's laws

As shown, two resistors are arranged in series with a $6.0\,\text{V}$ power supply. Determine the resistance of the variable resistor $R$ so that the potential difference across the $12\,\text{k}\Omega$ resistor is $1.0\,\text{V}$.

Potential dividers

A magnesium nucleus undergoes decay to form a nucleus X, with a $\beta^+$ particle being emitted. The decay is shown by the equation $^{23}_{12}\text{Mg} \rightarrow {}^{P}_{Q}\text{X} + {}^{0}_{+1}\beta^+$. What are the values of $P$ and $Q$?

Atoms, nuclei and radiation

An analogue ammeter with a range of $0$-$250\,\text{mA}$ has been placed in an electrical circuit. The diagram shows the ammeter’s display. What is the reading on the ammeter?

Electric current

During $\beta^-$ decay, a neutron within a nucleus turns into a proton. Which statement best describes the quark composition of the nucleus as the decay happens?

Fundamental particles

Students record the volume of a liquid by using three different measuring instruments X, Y and Z. The actual value of the liquid’s volume is $V$. The students’ outcomes are shown. How many of the instruments are precise and how many are accurate?

Errors and uncertainties

Which graph displays how the velocity $v$ of an object moving vertically downward in a vacuum varies with time $t$?

Equations of motion

A projectile is launched from point $P$ with speed $V$ at an angle $\theta$ to the horizontal. It reaches point $Q$, which is a horizontal distance $R$ from $P$. Air resistance is negligible. The acceleration of free fall is $g$. Which expression for $R$ is correct?

Equations of motion

A book with weight $W$ is resting on a table. A student tries to describe Newton’s third law of motion by stating that ‘action equals reaction’. If the book’s weight is the ‘action’ force, what force is the ‘reaction’ force?

Momentum and Newton's laws of motion

At the same instant, four balls are released from the top of a very tall tower. There is no wind. Which ball reaches the ground first?

Equations of motion

What would be a sensible estimate of the kinetic energy of an Olympic athlete sprinting in a $100\,\text{m}$ race?

Gravitational potential energy and kinetic energy

A rock in deep space heads towards a distant star and collides with a spacecraft that is at rest. Which result of the collision cannot happen?

Linear momentum and its conservation

A steel ball is falling through still air at constant (terminal) speed. The forces acting on the ball are upthrust, viscous drag and weight. In order of increasing magnitude, what are these three forces?

Equilibrium of forces

What does the term couple mean?

Turning effects of forces

As shown, four coplanar forces act on a rigid rod. The rod is hinged at point $P$. Which force creates the largest moment about point $P$?

Turning effects of forces

A rectangular book of weight $W$ and uniform thickness is held in a vertical plane with its longer sides arranged vertically. Which expression gives the approximate torque produced by the hand on the book?

Turning effects of forces

To derive the pressure equation $\Delta p = \rho g \Delta h$, several links between quantities are used. Which relationship is not involved in deriving this equation?

Density and pressure

A spring starts off with no compression and no extension. A force may be applied to it so that it becomes shorter by compression or longer by extension. What is the change in the elastic potential energy stored in the spring when it is extended and when it is compressed?

Elastic and plastic behaviour

A sample of gas is enclosed in a cylinder by a piston. Because the piston is frictionless and can move freely, the gas pressure stays constant at $1.80 \times 10^5\,\text{Pa}$. At first, the gas has a volume of $2.40 \times 10^{-4}\,\text{m}^3$. The gas now does $14.4\,\text{J}$ of work. What is the gas volume after this work has been done?

Density and pressure

A car with mass $500\,\text{kg}$ is initially stationary at point X on a slope, as shown. Its brakes are then released and, with the engine switched off, the car rolls downhill. By point Y the car has descended a vertical distance of $30\,\text{m}$ and is travelling at $11\,\text{m s}^{-1}$. Calculate the energy dissipated by frictional forces as the car moves from X to Y?

Gravitational potential energy and kinetic energy

Which expression is not suitable for calculating power?

Potential difference and power

What does the term unit of momentum mean?

Momentum and Newton's laws of motion

Stress $\sigma$ in a material is defined by the equation $\sigma = \dfrac{F}{A}$. Strain $\varepsilon$ in the same material is defined by the equation $\varepsilon = \dfrac{x}{L}$. Which expression gives the Young modulus of the material?

Stress and strain

Give one example of plastic deformation.

Elastic and plastic behaviour

A transverse progressive wave with wavelength $\lambda$ is produced on a stretched string. The graph illustrates how displacement $y$ varies with distance $x$ at one specific instant. The wave has displacement $+y_1$ when $x = \dfrac{\lambda}{8}$. What are the next two values of $x$ at which the displacement $y$ is once more equal to $+y_1$?

Progressive waves

The graph illustrates how the displacement of an air particle changes with time as a progressive sound wave moves through the air. The speed of sound in air is $330\,\text{m s}^{-1}$. What wavelength does the wave have?

Progressive waves

A microphone is attached to a cathode-ray oscilloscope (CRO). The microphone detects a sound wave that has a constant frequency. The CRO screen is displayed. The time-base is adjusted to $1.0\,\text{ms cm}^{-1}$. What is the frequency of the sound wave?

Progressive waves

A train whistle produces sound with frequency $500\,\text{Hz}$ while the train travels at a speed of $20\,\text{m s}^{-1}$ along a straight track. The train is moving straight towards a stationary observer beside the track, and then it goes past the observer. The speed of sound in air is $330\,\text{m s}^{-1}$. What is the difference between the frequencies of the sound heard by the observer before the train passes and after it has passed the observer?

Doppler effect for sound waves

Gamma-rays, microwaves, visible light and X-rays are four parts of the electromagnetic spectrum. Which option arranges these four parts in order of increasing wavelength?

Electromagnetic spectrum

For a stationary wave to be formed, two waves have to move through the same region in opposite directions. Which statement about the properties of these two waves must also be true?

Stationary waves

Sound travels through air at $330\,\text{m s}^{-1}$. Which size of architectural features in a large concert hall would produce the best diffraction of sound waves with frequency $0.44\,\text{kHz}$?

Diffraction

A double-slit interference pattern made with red light of wavelength $7.0 \times 10^{-7}\,\text{m}$ shows a fringe spacing of $3.5\,\text{mm}$. For the same arrangement of apparatus, what fringe spacing would be seen if blue light of wavelength $4.5 \times 10^{-7}\,\text{m}$ were used?

Interference

What is the horizontal part of the force shown?

Scalars and vectors

Light from a single wavelength source is incident normally on a diffraction grating. For each order of diffraction $n$, the diffraction angle $\theta$ is measured. The separation between neighbouring slits in the diffraction grating is $d$. A graph is drawn in order to find the wavelength of the light. Which graph should be drawn, and how is the wavelength obtained from the graph?

The diffraction grating

A particle carries a charge of $+2.0\,\text{mC}$ and is placed in a vertical uniform electric field. The particle experiences an upward electric force of $1.0 \times 10^{-2}\,\text{N}$. Determine the electric field strength?

Electric current

The diagram depicts two parallel metal plates that are linked to a d.c. power supply via a resistor. A uniform electric field exists in the space between the plates. Which alteration would reduce the electric field strength?

Potential difference and power

A wire is $12\,\text{cm}$ long and has a total of $5.1 \times 10^{22}$ free electrons. If a potential difference is applied across the two ends of the wire, the free electrons drift with an average speed of $4.0 \times 10^{-6}\,\text{m s}^{-1}$. Calculate the current in the wire.

Electric current

A battery has a rating of $9.0\,\text{V}$. What is implied by this?

Potential difference and power

The diagram illustrates a circuit in which two batteries are joined together. What is the value of the current $I$?

Kirchhoff's laws

The circuit diagram shows a cell with fixed internal resistance and an external resistor $R$. A student notes the ammeter and voltmeter values. She then adds a second identical external resistor in parallel with the first external resistor. What happens to the ammeter reading and to the voltmeter reading?

Practical circuits

A battery with electromotive force (e.m.f.) $E$ and negligible internal resistance is linked to four resistors with resistances $R_1$, $R_2$, $R_3$ and $R_4$. The currents $I_1$ and $I_2$ through the resistors are shown. Which equation is correct?

Kirchhoff's laws

In the circuit diagram, a potentiometer with total resistance $120\ \Omega$ is connected in parallel with a resistor whose resistance is $150\ \Omega$ and a resistor of resistance $R$. The battery has electromotive force (e.m.f.) $12\ \text{V}$ and negligible internal resistance. The voltmeter shows $0\ \text{V}$ when the slider on the potentiometer is positioned $\frac{1}{4}$ of the distance up from its lower end, as illustrated. Determine the resistance $R$.

Potential dividers

A beam of $\alpha$-particles is directed at a thin gold foil. One $\alpha$-particle has a head-on collision with a gold nucleus and is sent back along its original path. Which statement could account for the gold nucleus having a recoil speed that is small compared with the recoil speed of the $\alpha$-particle?

Linear momentum and its conservation

The diagram presents two micrometer readings. What is the difference between these two readings?

Errors and uncertainties

A hadron consists of three quarks. This hadron is charged. What could be a possible quark composition of this hadron?

Fundamental particles

A circular disc has a measured diameter of $(7.0 \pm 0.1)\,\text{mm}$. Determine its area and the absolute uncertainty in the area.

Errors and uncertainties

The diagram presents a velocity-time graph for a car. What distance is travelled in the first $4.0\,\text{s}$?

Equations of motion

A steel ball is released from rest at a height $h$ above the ground. It reaches the ground after a time $t$. The experiment is carried out again for several different heights. The graph shows how $h$ varies with $t^2$ for the ball. The gradient of the graph is $G$. Which expression gives the acceleration of the ball?

Equations of motion

Two masses, $M$ and $m$, are joined by an inextensible string that runs over a frictionless pulley. Mass $M$ is on a frictionless slope inclined at an angle $\theta$ to the horizontal. Initially, both masses are held at rest and are then released. Mass $M$ moves with acceleration down the slope. Which expression must be correct?

Momentum and Newton's laws of motion

The masses and weights of four distinct objects on the surfaces of four different planets are shown. On which planet is the acceleration of free fall at the surface the lowest?

Momentum and Newton's laws of motion