May/June 2015

Which one is an SI base unit?

SI units

What would be a reasonable estimate for the average gravitational force acting on a fully grown woman standing on Earth?

Momentum and Newton's laws of motion

A molecule with mass $m$ and speed $v$ collides with a wall while moving at right angles to the wall. The collision is elastic. What changes are produced in the molecule’s momentum and kinetic energy by the collision?

Linear momentum and its conservation

A child riding on a sledge moves down a hill with acceleration $a$. The hill is inclined at an angle $\theta$ to the horizontal. The combined mass of the child and the sledge is $m$. The acceleration due to free fall is $g$. What is the friction force $F$?

Momentum and Newton's laws of motion

A box with mass $8.0\,\text{kg}$ is at rest on a horizontal rough surface. A string attached to the box runs over a smooth pulley and carries a $2.0\,\text{kg}$ mass at the other end. Once the box is released, a frictional force of $6.0\,\text{N}$ acts on it. What is the acceleration of the box?

Momentum and Newton's laws of motion

What is meant by the force acting on a body?

Momentum and Newton's laws of motion

A uniform metre rule is supported at the $34.0\,\text{cm}$ mark, as illustrated. The rule is in equilibrium when a $64\,\text{g}$ mass is suspended from the $4.0\,\text{cm}$ mark. Calculate the mass of the metre rule.

Turning effects of forces

A group of nine dogs can drag a sledge with a total force of $800\,\text{N}$ at a speed of $1.5\,\text{m s}^{-1}$ for $360$ minutes. What is the mean work done by each dog over this period?

Energy conservation

Which of the following statements is correct?

Physical quantities

The diagram illustrates a pump known as a hydraulic ram. For one pump of this type, the long approach pipe contains $500\,\text{kg}$ of water. When the speed of this water reaches $2.0\,\text{m s}^{-1}$, a valve closes, and the kinetic energy of the water is then used to raise a small amount of water through a height of $15\,\text{m}$. The pump has an efficiency of $10\%$. What mass of water can be raised $15\,\text{m}$?

Gravitational potential energy and kinetic energy

A motor drives a conveyor belt so that it moves with velocity $v$. Sand falls straight down onto the belt at a rate of $m\,\text{kg s}^{-1}$. What extra power is required to keep the conveyor belt moving at constant speed when the sand begins to land on it?

Momentum and Newton's laws of motion

Which pair includes one vector and one scalar quantity?

Scalars and vectors

Three descriptions of different material types are given below. $1$ a polycrystalline material containing large numbers of tiny crystals $2$ an amorphous material with very little, or no, ordered molecular arrangement $3$ a polymeric material made from long chains of molecules Which row correctly pairs the descriptions with nylon, copper and glass?

Elastic and plastic behaviour

The diagram illustrates the arrangement of atoms in a specific crystal. Each atom is positioned at a corner of a cube. The mass of each atom is $3.5 \times 10^{-25}\,\text{kg}$. The density of the crystal is $9.2 \times 10^3\,\text{kg m}^{-3}$. What is the smallest separation between the centres of two neighbouring atoms?

Density and pressure

The graph below was drawn from an experiment using a metal wire. The shaded region shows the total strain energy stored when the wire is stretched. What labels should be used for the axes?

Stress and strain

The graph illustrates how the extension of a spring changes as the applied force varies. If no force acts on the spring, its length is $1.0\,\text{cm}$. What increase occurs in the strain energy stored in the spring when its length rises from $2.0\,\text{cm}$ to $3.0\,\text{cm}$?

Elastic and plastic behaviour

A sound wave travels through air at a speed of $320\,\text{m s}^{-1}$. The graph shows how the displacement of an air particle caused by this wave changes with time. Which statement about the sound wave is correct?

Transverse and longitudinal waves

A wave with frequency $15\,\text{Hz}$ moves through a medium at $24\,\text{m s}^{-1}$. What is the phase difference between two points $2\,\text{m}$ apart?

Progressive waves

A wave with amplitude $a$ has intensity $3.0\,\text{W m}^{-2}$. What is the intensity of another wave with the same frequency but amplitude $2a$?

Progressive waves

An electromagnetic wave has a wavelength that is numerically of the same order of magnitude as the diameter of a nucleus. In what region of the electromagnetic spectrum does this wave lie?

Electromagnetic spectrum

The diagram represents a stationary wave on a string at two moments when the vertical displacement is greatest. The distance shown is 90 cm. The wave has a frequency of $12\,\text{Hz}$. What is the wave speed?

Stationary waves

At the open end of a pipe of length $l$ that is closed at the opposite end, a loudspeaker producing sound at frequency $f$ is positioned. A standing wave forms inside the pipe. A set of pipes is then arranged using either one loudspeaker or two loudspeakers of frequency $f$. The paired loudspeakers oscillate in phase with one another. In which pipe is a standing wave present?

Stationary waves

For a vehicle travelling at speed $v$, if a constant braking force is exerted, the distance $d$ travelled as it comes to rest is described by $d = kv^2$, where $k$ is a constant. If $d$ is given in metres and $v$ is given in metres per second, the constant takes the value $k_1$. When the distance is measured in metres and the speed is measured in kilometres per hour, what is the value of the constant?

SI units

In a double-slit experiment, the separation of the fringes on a screen was too small to measure. What change would make the fringe spacing larger?

Interference

A potential difference of $1000\,\text{V}$ is applied across two parallel metal plates that are separated by a distance of $2\,\text{mm}$. What is the electric field strength in the region between the plates?

Potential difference and power

A droplet of oil carries charge $-q$ and lies between two horizontal metal plates, as illustrated. The plates are separated by a distance $d$. It is found to remain at rest when the upper plate is at potential $+V$ and the lower plate is at potential $-V$. Under these conditions, what is the weight of the droplet?

Potential difference and power

The diagrams illustrate two different circuits. In each circuit, the cells have the same electromotive force and zero internal resistance. Each of the three resistors has resistance $R$. In the circuit on the left, the power dissipated in the resistor is $P$. What is the total power dissipated in the circuit on the right?

Potential difference and power

Which one of these equations correctly connects some of the following quantities: potential difference (p.d.) $V$, current $I$, resistance $R$, charge $Q$, energy $E$, power $P$, time $t$?

Potential difference and power

An electric battery’s deliverable charge is measured in ampere-hours. For instance, a battery with capacity $40$ ampere-hours could, if fully charged, provide $0.2\,\text{A}$ for $200$ hours. What is the maximum energy a fully charged $12\,\text{V}$, $40$ ampere-hour battery could supply?

Potential difference and power

A battery of e.m.f. $E$ and internal resistance $r$ is connected in series with a variable external resistor. The external resistance $R$ is gradually raised from zero. Which statement is correct? (Ignore any temperature effects.)

Potential difference and power

A battery with electromotive force (e.m.f.) $6.0\,\text{V}$ and negligible internal resistance is joined in series to a resistor of resistance $6.0\,\Omega$ and a variable resistor whose resistance can vary from zero to $4.0\,\Omega$. A voltmeter is placed across the variable resistor. The resistance of the variable resistor is adjusted. What range of readings can the voltmeter show?

Potential difference and power

The wire RST is joined to a second wire XY, as illustrated. Each wire has length $100\,\text{cm}$ and a resistance per unit length of $10\,\Omega\,\text{m}^{-1}$. Calculate the total resistance between X and Y.

Resistance and resistivity

When $\alpha$-particles are aimed at gold leaf 1 nearly all $\alpha$-particles travel straight through with no deflection, 2 a small number of $\alpha$-particles are scattered through large angles. What explains these observations?

Atoms, nuclei and radiation

A whale emits sound waves at a frequency of $5\,\text{Hz}$. These waves are picked up by a microphone and shown on an oscilloscope. What is the time-base setting on the oscilloscope?

Progressive waves

The nuclide $^{222}_{86}\text{Rn}$ undergoes a chain of decays, step by step, until the nuclide $^{206}_{82}\text{Pb}$ is produced. In this decay chain, four of the nuclides that are produced emit $\alpha$-particles. All of the remaining nuclides emit $\beta$-particles. How many of the nuclides produced in the decay chain are $\beta$-particle emitters?

Atoms, nuclei and radiation

The needle’s angular deflection in an ammeter changes with the current through the ammeter, as illustrated by the graph. Which diagram could show what the scale on this meter looks like?

Practical circuits

The strain energy $W$ stored in a spring depends on its spring constant $k$ and its extension $x$. This spring follows Hooke’s law, and $W$ is found by using the equation below. $W = \frac{1}{2}kx^2$ The spring constant is $100 \pm 2\,\text{N m}^{-1}$ and the extension is $0.050 \pm 0.002\,\text{m}$. What percentage uncertainty is there in the calculated value of $W$?

Errors and uncertainties

A sphere is let go and drops. Its starting acceleration decreases until it finally moves with a constant terminal velocity. Which displacement-time graph most accurately shows the sphere’s motion?

Non-uniform motion

An insect launches upwards with an initial vertical velocity of $1.0\,\text{m s}^{-1}$ and attains a greatest height of $3.5 \times 10^{-2}\,\text{m}$. If the deceleration is constant, what is the magnitude of the deceleration?

Equations of motion

A body moving with uniform acceleration $a$ changes its velocity from $u$ to $v$ over a time $t$. Which expression would not produce the correct displacement of the body during the time $t$?

Equations of motion

Which definition is correct and uses quantities only, rather than units?

Physical quantities

A firework rocket is launched straight upwards. Its fuel burns and gives the rocket a steady upward force. Once $5\,\text{s}$ have passed, all the fuel has been used up. Air resistance is negligible. What is the acceleration before and after $5\,\text{s}$?

Momentum and Newton's laws of motion

Trolley X, travelling on a horizontal frictionless track, collides with stationary trolley Y. The two trolleys stick together and then continue moving as one. Which statement concerning this interaction is correct?

Linear momentum and its conservation

An astronaut launches a stone with a horizontal velocity close to the Moon’s surface. Which row describes the horizontal and vertical forces acting on the stone after it is released?

Momentum and Newton's laws of motion

Newton’s third law of motion is commonly expressed as ‘Every action (force) has an equal and opposite reaction.’ A book is at rest on a table. If the book’s weight is the ‘action’ force, what force is the corresponding ‘reaction’?

Momentum and Newton's laws of motion

A ladder rests on icy (frictionless) ground and is leaning against a rough wall. The moment it is let go, it starts to slip. Which diagram correctly shows the directions of the forces $P$, $W$ and $R$ acting on the ladder while it is sliding?

Equilibrium of forces

A uniform solid block has weight $500\,\text{N}$, width $0.4\,\text{m}$ and height $0.6\,\text{m}$. It is positioned on the edge of a step with depth $0.8\,\text{m}$, as illustrated. The block is pushed over the step edge and turns through $90^{\circ}$ before settling so that the $0.6\,\text{m}$ edge is horizontal. What is the change in gravitational potential energy of the block?

Gravitational potential energy and kinetic energy

The diagram illustrates a hydroelectric power station. The reservoir is connected to the turbines by a pipe with a uniform cross-sectional area. Water moves from X to Y at a constant speed. Which statement about the change in the energy of the water as it travels from X to Y is correct?

Gravitational potential energy and kinetic energy

A fisherman raises a fish with mass $250\,\text{g}$ from rest by a vertical distance of $1.8\,\text{m}$. The fish reaches a speed of $1.1\,\text{m s}^{-1}$. What energy is gained by the fish?

Gravitational potential energy and kinetic energy

Water from a reservoir is delivered to the turbine of a hydroelectric system at a mass flow rate of $500\,\text{kg s}^{-1}$. The reservoir is located $300\,\text{m}$ above the turbine level. The generator driven by the turbine produces an electrical output of $200\,\text{A}$ at a potential difference of $6000\,\text{V}$. Calculate the efficiency of the system.

Gravitational potential energy and kinetic energy

Which row correctly shows how the molecules are arranged and how they move in liquid water and in ice when each is at a temperature of $0^{\circ}\text{C}$?

Density and pressure

For a gas molecule, the mean kinetic energy $E$ is represented by $E = \frac{3}{2} k T$, with $T$ denoting the absolute (kelvin) temperature. What are the SI base units of $k$?

SI units

The greatest pressure granite rock can tolerate is $2.0 \times 10^{8}\,\text{N m}^{-2}$. If the pressure rises above this value, the rock starts to behave like a liquid. Granite has a density of $2.7 \times 10^{3}\,\text{kg m}^{-3}$. How tall would a mountain made only of granite be if its base were just on the point of flowing?

Density and pressure

To find the Young modulus of a wire, a number of readings are recorded. In which row is it not possible to make the measurement directly using the apparatus given?

Stress and strain

A long, thin metal wire is hung vertically from a fixed support. Masses are attached to its lower end. The load at the lower end is raised from zero and then reduced again to zero. The diagram shows the force-extension graph obtained. At what point on the graph would the elastic limit be located?

Elastic and plastic behaviour

The diagram shows a steel tube whose wall thickness $w$ is tiny compared with the tube’s diameter. A force $T$, acting parallel to the tube’s axis, puts the tube in tension. In order to lower the stress in the tube material, the wall is to be made thicker. If the tube diameter and the tension stay unchanged, which wall thickness gives half the stress?

Stress and strain

The diagram shows two light waves with the same frequency. What might the phase difference be between these two waves?

Interference

A sound wave moves at a speed of $330\,\text{m s}^{-1}$ and has a frequency of $50\,\text{Hz}$. What could be a possible separation between two points on the wave with a phase difference of $60^{\circ}$?

Progressive waves

Which of the following is not a necessary condition for an interference pattern to be seen from waves coming from two sources?

Interference

Source $S$ produces microwaves at a steady amplitude. The microwaves travel to a metal screen $P$ and are reflected. A stationary wave is set up between $S$ and $P$. The wavelength of the microwaves is much smaller than the separation between $S$ and $P$. A detector $Q$ is then moved from $S$ to $P$ at a slow, constant speed. What happens to the amplitude of the signal detected by $Q$?

Stationary waves

A wave pattern was seen even though the source of the waves could not be observed. The diagram shows the pattern. What can produce this pattern?

Interference

A positive charge and a negative charge, each with the same magnitude, are separated by a small distance. Which diagram most accurately shows the electric field associated with them?

Scalars and vectors

An analogue ammeter uses a pointer that travels across a scale. After being used for a long time, the pointer no longer returns completely to zero when the current is switched off, and the meter has become less sensitive at larger currents than it is at smaller currents. Which diagram best shows the calibration graph required to give an accurate current reading?

Errors and uncertainties

An oil drop of mass $m$, containing $n$ extra electrons, is kept at rest in the uniform electric field between two horizontal plates spaced a distance $d$ apart. The voltage across the plates is $V$, the elementary charge is $e$ and the acceleration of free fall is $g$. Determine the value of $n$.

Potential difference and power

Which unit does not appear in either the definition of the coulomb or the definition of the volt?

SI units

If a thin metal wire is pulled taut, its length increases while its thickness decreases. As a result, the resistance of the wire changes. The wire’s volume stays unchanged. Which graph could show how the resistance $R$ varies with extension $x$ of the wire?

Resistance and resistivity

Which statement is incorrect?

Physical quantities

A cell with e.m.f. $E$ transfers a charge $Q$ to an external circuit. Which statement is correct?

Potential difference and power

Each of Kirchhoff's two laws assumes that one physical quantity remains conserved. Which row gives Kirchhoff's first law and identifies the conserved quantity?

Kirchhoff's laws

A potential divider circuit is made from fixed resistors with resistances $2.0\,\Omega$ and $4.0\,\Omega$ joined in series with a $3.0\,\Omega$ resistor that has a sliding contact. These components are connected across a battery with e.m.f. $9.0\,\text{V}$ and zero internal resistance, as shown. What are the greatest and the smallest output voltages for this potential divider circuit?

Potential dividers

A cell with e.m.f. $2.0\,\text{V}$ and negligible internal resistance is linked to a resistor network as shown. What is the current $I$?

Kirchhoff's laws

An experiment in which $\alpha$-particles were deflected by a gold foil led to new understanding of atomic structure. Which conclusion can be deduced from the experimental results?

Atoms, nuclei and radiation

A radioactive material contains many nuclei of the same kind that emit $\beta$-particles. After this emission, which property of the nuclei stays unchanged?

Atoms, nuclei and radiation

The arrow shows the vector $\vec{R}$. Which diagram does not show $\vec{R}$ split into two perpendicular components?

Scalars and vectors

A uranium-238 nucleus, $^{238}_{92}\text{U}$, decays in a nuclear process to produce uranium-234, $^{234}_{92}\text{U}$. Which decay sequence could lead to this outcome?

Atoms, nuclei and radiation

A power supply with electromotive force (e.m.f.) $50\,\text{V}$ and negligible internal resistance is connected in series with resistors of resistance $100\,\Omega$ and $5\,\Omega$, as illustrated. A voltmeter is used to measure the potential difference (p.d.) across the $5\,\Omega$ resistor, and an ammeter is used to measure the current in the circuit. Which ranges would be appropriate for the ammeter and for the voltmeter?

Practical circuits

One sheet of aluminium foil is folded two times so that a pile of four sheets is formed. The measured total thickness of this pile is $(0.80 \pm 0.02)\,\text{mm}$. A digital calliper with a zero error of $(-0.20 \pm 0.02)\,\text{mm}$ is used for the measurement. What is the percentage uncertainty in the calculated thickness of one sheet?

Errors and uncertainties

In an experiment designed to find the acceleration of free fall $g$, a ball bearing is supported by an electromagnet. Once the current to the electromagnet is turned off, a clock begins and the ball bearing drops. After it has fallen a distance $h$, the ball bearing hits a switch that stops the clock, which records the time $t$ for the fall. If systematic errors make $t$ and $h$ be measured wrongly, which error would have to make $g$ seem larger than $9.81\,\text{m s}^{-2}$?

Errors and uncertainties

A stone is launched horizontally from the summit of a cliff. Air resistance may be ignored. Which graph illustrates how the vertical component of the stone’s velocity changes with time?

Equations of motion

A sprinter completes a $100\,\text{m}$ race in a straight line. Starting from the blocks, he increases his speed with a constant acceleration of $2.5\,\text{m s}^{-2}$ until he reaches a top speed of $10\,\text{m s}^{-1}$. He then continues at this speed until the finish line is crossed. How long does the sprinter take to complete the race?

Equations of motion

Which statement contains the correct unit?

SI units

Which one of the following gives the statement of the principle of conservation of momentum?

Linear momentum and its conservation

A moving object collides with an object at rest. The collision is inelastic, and the objects then travel away together. Which row gives the possible values of the system’s total momentum and total kinetic energy before and after the collision?

Linear momentum and its conservation

Two balls $X$ and $Y$ are travelling towards one another with speeds of $5\,\text{m s}^{-1}$ and $15\,\text{m s}^{-1}$ respectively. They undergo a perfectly elastic head-on collision, and after the collision ball $Y$ moves to the right at a speed of $7\,\text{m s}^{-1}$. What are the speed and direction of ball $X$ after the collision?

Linear momentum and its conservation

A timber block is resting freely on brackets $4.0\,\text{m}$ above the ground, as illustrated. A bullet with mass $5.0\,\text{g}$ is fired straight upwards into the timber block of mass $95\,\text{g}$. It becomes embedded in the block. As a result of the impact, the block moves up beyond its supporting brackets. The bullet strikes the block at a speed of $200\,\text{m s}^{-1}$. What height above the ground does the block reach at the top of its motion?

Linear momentum and its conservation

Four cuboids, each having the same length, breadth and height, are placed in water. They are maintained at an equal depth and in the same orientation by vertical rods, as illustrated. Water has density $\rho$. Cuboid $W$ is made of a material with density $4\rho$. Cuboid $X$ is made of a material with density $2\rho$. Cuboid $Y$ is made of a material with density $\rho$. Cuboid $Z$ is made of a material with density $0.5\rho$. Which statement is correct?

Density and pressure

An air bubble in a tank of water is moving upwards at constant velocity. The forces acting on the bubble are $X$, $Y$ and $Z$ as shown. Which statement describes these three forces?

Equilibrium of forces

The diagrams show systems of coplanar forces acting at a point. The lengths of the force vectors indicate the sizes of the forces. Which system of forces is in equilibrium?

Equilibrium of forces

In an engine, the gas exerts work on a piston with cross-sectional area $80\,\text{cm}^2$. The pressure acting on the piston remains constant at $4.6 \times 10^5\,\text{Pa}$. What amount of work is carried out by the gas on the piston as it travels a distance of $25\,\text{cm}$?

Density and pressure

An aeroplane, when fully loaded, has a total mass of $1.2 \times 10^5\,\text{kg}$ as it rises after take-off. It is ascending at an angle of $23^\circ$ above the horizontal and moving at a speed of $50\,\text{m s}^{-1}$. What is the rate at which its potential energy is increasing at this moment?

Gravitational potential energy and kinetic energy

A horizontal force $F$ is exerted on a frictionless trolley as it moves through a distance $s$, and the trolley’s kinetic energy changes from $4.0\,\text{J}$ to $8.0\,\text{J}$. If the trolley is then acted on by a force of $2F$ across a distance of $2s$, what would the initial kinetic energy of $4.0\,\text{J}$ change to?

Energy conservation

What does the joule (J) equal in SI base units?

SI units

As ice melts, it contracts. Which row shows ice changing into water correctly?

Density and pressure

A tube shaped like a W contains two separate portions of mercury, and each is exposed to the atmosphere. A pocket of air at pressure $P$ is trapped between them. The diagram labels two vertical distances $x$ and $y$. Atmospheric pressure is the same as the pressure produced by a column of mercury $760\,\text{mm}$ high. The pressure $P$ is written in this form. Which combinations of $x$, $y$ and $P$ could be correct?

Density and pressure

A steel rod with a circular cross-section is subjected to tension $T$, as illustrated. The diameter of the wider section is twice the diameter of the narrower section. What is the value of $\dfrac{\text{stress in the wide portion}}{\text{stress in the narrow portion}}$?

Stress and strain

The graph illustrates the non-linear force-extension curve for a wire formed from a new composite material. What might be the strain energy stored in the wire when it is extended elastically to point $P$?

Elastic and plastic behaviour

The diagram illustrates the stress-strain graph for bone. What value does the Young modulus of bone have?

Stress and strain

A cathode-ray oscilloscope (c.r.o.) is used to present the trace of a sound wave. The time-base is set at $5\,\mu\text{s mm}^{-1}$. What frequency does the sound wave have?

Practical circuits

A wave pulse travels along a stretched rope in the direction indicated. Which diagram shows correctly how the displacement $s$ of the particle P in the rope changes with time $t$?

Progressive waves

The table shows statements about stationary and progressive waves. Which row is correct?

Stationary waves

Which electromagnetic wave would produce the strongest diffraction effect for an atomic lattice with a spacing of about $10^{-10}\,\text{m}$?

Diffraction

At points X and Y, wave generators create water waves with identical wavelength. At Z, the waves arriving from X have the same amplitude as those arriving from Y. The distances XZ and YZ are shown. If the wave generators work in phase, the oscillation amplitude at Z is zero. What might the wavelength of the waves be?

Interference

An aeroplane travels at $200\,\text{km h}^{-1}$ in still air. The wind is blowing from the west at a speed of $85.0\,\text{km h}^{-1}$. What direction should the pilot steer the aeroplane so that it flies due north?

Scalars and vectors

A molecule can be modelled as an electric dipole made up of two equal point charges with opposite sign, separated by a fixed distance. As shown, the molecule enters a vertical uniform electric field while travelling with constant horizontal velocity. The positive and negative charges of the molecule enter the field simultaneously. Which row gives the velocity of the molecule in the field?

Turning effects of forces

Which diagram most accurately shows the electric field between two point charges with equal magnitude and opposite sign?

Electric current

An electric motor is attached to a pedal bicycle. The cyclist activates the motor for $3.0\,\text{minutes}$. A steady current of $3.5\,\text{A}$ is taken by the electric motor from a battery with a terminal voltage of $24\,\text{V}$. What is the energy supplied by the battery?

Potential difference and power

The diagram illustrates a simple circuit. Which statement is correct?

Practical circuits

A circuit is arranged by connecting a resistor of resistance $R$ across the terminals of a battery with electromotive force (e.m.f.) $9.0\,\text{V}$ and a constant internal resistance $r$. A charge of $6.0\,\text{C}$ passes through the resistor in a time of $2.0\,\text{minutes}$, producing $48\,\text{J}$ of thermal energy dissipation. What is the internal resistance $r$ of the battery?

Practical circuits

A source with e.m.f. $9.0\,\text{mV}$ and internal resistance $6.0\,\Omega$ is connected across a galvanometer whose resistance is $30\,\Omega$. What current flows in the galvanometer?

Practical circuits

A box has four terminals P, Q, R and S and includes two identical resistors. If a battery with electromotive force (e.m.f.) $E$ and negligible internal resistance is connected across PS, a high-resistance voltmeter placed across QR shows $\frac{E}{2}$. Which diagram indicates the correct arrangement of the two resistors inside the box?

Potential dividers

The diagram illustrates a section of a current-carrying circuit. The ammeter has negligible resistance. What current is indicated by the ammeter?

Practical circuits

Nucleus P undergoes decay in two steps to form nucleus Q. Which decay pathway would give nucleus Q the greatest number of neutrons?

Atoms, nuclei and radiation

A neutral atom contains a nucleus shown by the symbol $^{133}_{55}\text{Cs}$. What are the numbers of protons, neutrons and electrons in this atom?

Atoms, nuclei and radiation

A student is provided with a reel of wire with a diameter smaller than $0.2\,\text{mm}$ and must determine the density of the metal. Which pair of instruments would be most appropriate for measuring the volume of the wire?

Errors and uncertainties

The nuclear equation for a fission process is given below. $^{235}_{92}\text{U} + ^{1}_{0}\text{n} \rightarrow ^{93}_{X}\text{Rb} + ^{141}_{55}\text{Cs} + Y\,^{1}_{0}\text{n}$ Determine the values of $X$ and $Y$?

Atoms, nuclei and radiation

A ruler is used by four different students to measure the length of a $15.0\,\text{cm}$ pencil. The measurements are shown on four separate charts. Which chart displays measurements that are precise but not accurate?

Errors and uncertainties

In a basic electrical circuit, the current through a resistor is measured as $(2.50 \pm 0.05)\,\text{mA}$. The resistor is labelled with a value of $4.7\,\Omega \pm 2\%$. If these measurements were applied to determine the power dissipated in the resistor, what percentage uncertainty would the result have?

Errors and uncertainties

A raindrop is released from rest and moves straight down through air. The graph shows how its speed varies with time. Which statement about the raindrop is correct?

Non-uniform motion

The electric car’s velocity varies as illustrated. What is the car’s acceleration?

Equations of motion

A body falling through a uniform gravitational field experiences air resistance. This air resistance increases until terminal velocity is attained. Which factor does not influence its terminal velocity?

Non-uniform motion