Oct/Nov 2011

Which statement that uses prefixes of the base unit metre (m) is incorrect?

SI units

What does the term force on a body mean?

Momentum and Newton's laws of motion

A car begins from rest. The graph shows the car’s momentum plotted against time. What does the gradient of the graph represent at a particular time?

Momentum and Newton's laws of motion

An ice-hockey puck moves across a horizontal surface of frictionless ice. It undergoes an inelastic collision with a wall that is at right angles to its direction of travel, and afterwards it bounces back along the same path. Which graph shows how the puck’s momentum $p$ varies with time $t$?

Momentum and Newton's laws of motion

A ladder is balanced in equilibrium, with its foot on rough ground and its top leaning against a rough wall. Its weight $W$ acts through the centre of gravity $G$. Additional forces act on the ladder at $P$ and at $Q$. These forces are $P$ and $Q$ respectively. Which vector triangle shows the forces acting on the ladder?

Equilibrium of forces

A ruler of length $0.30\,\text{m}$ is supported at its midpoint. Forces of equal size, $2.0\,\text{N}$, act in opposite directions at the two ends of the ruler, producing a couple as shown. What is the magnitude of the torque of the couple on the ruler in the position shown?

Turning effects of forces

The diagram illustrates a child’s balancing game. The wooden rod is uniform, and every ring has the same mass. Two rings are attached to peg 13 and one ring is attached to peg 1. At which hook should a fourth ring be placed so that the rod is balanced?

Turning effects of forces

The diagram depicts a particle X, with kinetic energy $E_k$, just before it collides with a stationary particle Y. The two particles have equal mass. Following the collision, X and Y continue moving together as one larger particle. What amount of kinetic energy is lost during the collision?

Linear momentum and its conservation

The table’s first column shows four examples of work being carried out. The second column provides further detail about each action. Which row is incorrect?

Energy conservation

A trolley moves along a track from P to Q. Its potential energy at Q is $50\,\text{kJ}$ lower than it is at P. At P, the trolley has kinetic energy of $5\,\text{kJ}$. As it travels from P to Q, it does $10\,\text{kJ}$ of work against friction. What is the kinetic energy of the trolley at Q?

Energy conservation

An electric motor must deliver $120\,\text{W}$ of mechanical output power. The motor has an efficiency of $80\%$. Which row is correct?

Potential difference and power

A mass of $80\,\text{kg}$ Olympic athlete takes part in a $100\,\text{m}$ race. What is the most suitable estimate for his average kinetic energy over the race?

Gravitational potential energy and kinetic energy

A mass $m$ is placed in space within a uniform gravitational field. As the mass travels a displacement $x$, from P to Q, it loses potential energy equal to $E$. Which row gives the correct value for the magnitude and the direction of the acceleration due to gravity in this field?

Gravitational potential energy and kinetic energy

Why does the pressure rise when a sealed container of gas is heated?

Density and pressure

Pollen grains are dispersed in a liquid and brightly illuminated. When viewed through a microscope, they are observed to be moving in a continuous random way. What is the reason for this?

Atoms, nuclei and radiation

The Young modulus of steel is measured with a steel wire of length and is found to be $E$. A second experiment is then done with a wire made from the same steel, but with half the length and half the diameter. What value is obtained for the Young modulus in the second experiment?

Stress and strain

A rubber band is stretched and then allowed to return to its original length. The diagram displays the force-extension graph for this process. As the force rises, the curve traces the route OPQ to extension $e$. As the force falls, the curve follows QRO to go back to zero extension. The region marked X lies between the curves OPQ and QRO. The region marked Y is enclosed by the curve QRO and the horizontal axis. Which statement about the process is correct?

Elastic and plastic behaviour

When explaining how a spring behaves, the spring constant is used. Different loads are applied to stretch the spring by varying amounts. To determine the spring constant, which quantities are needed?

Elastic and plastic behaviour

A metal cube with side $l$ is held in a vice and compressed elastically by two opposing forces $F$. What relationship will $\Delta l$, the amount of compression, have with $l$?

Stress and strain

P is a source that gives out infra-red radiation, and Q is a source that gives out ultra-violet radiation. The numbers in the table are proposed wavelength values for the radiation emitted by P and Q. Which row is correct?

Electromagnetic spectrum

The diagram gives a top view of a double slit interference experiment. L is a monochromatic light source with a vertical filament. B is a barrier containing two narrow vertical slits and S is a screen on which interference fringes are produced. The intensity is $I$ at the point on the screen where the centre of the fringe pattern is formed. What is the intensity, at that same point, when one slit is covered?

Interference

Travelling waves with wavelength $20\,\text{cm}$ are set up in the air columns inside a closed pipe $P$ and an open pipe $Q$. The lengths of the pipes are shown. In which pipe or pipes are stationary waves formed?

Stationary waves

Which set of quantities consists only of vectors?

Scalars and vectors

Coherent waves originate at $P$ and at $Q$ and spread out in every direction. The line $RS$ lies halfway between $P$ and $Q$ and is perpendicular to the line joining $P$ and $Q$. The distance $RS$ is much greater than the distance $PQ$. Along which line, or lines, is an interference pattern seen?

Interference

In air, two horizontal parallel plate conductors are 5.0\,\text{mm} apart. The lower plate is earthed, while the upper plate is at a potential of +50\,\text{V}. What is the electric field strength $E$ at the point halfway between the plates?

Potential difference and power

The diagram depicts an insulating rod with equal and opposite point charges at each end. An electric field of strength $E$ acts on the rod downward. Which row is correct?

Turning effects of forces

Which of the following statements about electrical resistivity is correct?

Resistance and resistivity

Which equation is the correct one linking 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

Which statement is incorrect?

Errors and uncertainties

A cell with e.m.f. $E$ and internal resistance $r$ is connected in series to a switch $S$ and an external resistor of resistance $R$. The p.d. across $P$ and $Q$ is $V$. When $S$ is closed,

Practical circuits

Four circuits are assembled using a cell, an ammeter and two resistors with equal resistance. Apart from the resistors, none of the other components in the circuits has resistance. In which circuit will the ammeter give the largest reading?

Electric current

Three resistors with resistances $R$, $2R$ and $3R$ are connected in parallel. If $I$ is used for the current in the resistor of resistance $R$, which row shows how the currents in the resistors are related?

Electric current

The diagram illustrates a potential divider circuit set up to supply a variable output p.d. Which row shows the range of output p.d. that can be obtained?

Potential dividers

A cylindrical tube rolling down a slope with inclination $\theta$ travels a distance $L$ in time $T$. The relationship between these quantities is $L \left( 3 + \frac{a^2}{P} \right) = Q T^2 \sin \theta$ where $a$ represents the internal radius of the tube and $P$ and $Q$ are constants. Which row gives the correct units for $P$ and $Q$?

SI units

An atomic nucleus releases a $\beta$-particle. How does this affect the proton number and the nucleon number of the nucleus?

Atoms, nuclei and radiation

The Young modulus for the material of a wire is to be determined. The Young modulus $E$ is given by the equation below. $E = \frac{4Fl}{\pi d^2 x}$ A known force is used to extend the wire, and the measurements below are obtained. Which measurement has the greatest effect on the uncertainty in the value of the Young modulus calculated?

Stress and strain

A ball starts from rest on a smooth slope $XY$. It travels down the slope, continues over a smooth horizontal surface $YZ$ and rebounds inelastically at $Z$. It then travels back to $Y$ and is momentarily at rest at a point somewhere on $XY$. Which velocity-time graph best shows the ball's motion?

Equations of motion

A tennis ball is dropped from rest at the top of a tall building. Which graph best shows how the acceleration $a$ of the ball changes with time $t$ as it falls, assuming that the effect of air resistance is not negligible?

Non-uniform motion

A boy throws a ball straight upwards. The ball climbs to its greatest height, where it is briefly at rest, and then returns to his hands. Which row shows the ball’s acceleration at different points in its motion? (Take vertically upwards as positive. Ignore air resistance.)

Equations of motion

A body descending in a uniform gravitational field experiences air resistance. The air resistance increases until terminal velocity is attained. Which factor has no effect on its terminal velocity?

Non-uniform motion

Which physical quantity may be expressed in electronvolts (eV)?

Energy conservation

A group of students are investigating the principle of conservation of momentum using a small truck moving across a frictionless surface. Sand is poured into the truck while it goes past X. At Y, a trapdoor in the base of the truck opens and the sand drops out. How does the velocity of the truck alter when the sand is added to the truck at X and then exits the truck at Y?

Linear momentum and its conservation

An object of mass $20\,\text{kg}$ moves at a steady speed of $6.0\,\text{m s}^{-1}$. It then collides with another object of mass $12\,\text{kg}$ moving at a steady speed of $15\,\text{m s}^{-1}$ in the opposite direction. After the impact, the objects remain stuck together. Determine the speed of the objects immediately after the collision.

Linear momentum and its conservation

An object has two possible displacement vectors, $\vec{P}$ and $\vec{Q}$. Which vector most accurately shows the resultant displacement $(\vec{P} - \vec{Q})$ of the object?

Scalars and vectors

Two forces acting in the plane of the wheel’s rim are applied. Both forces have the same magnitude. Which force arrangement produces only a couple?

Turning effects of forces

A trailer with weight $30\,\text{kN}$ is attached to a cab at X, as shown in the diagram. What is the upward force applied by the cab on the trailer at X?

Equilibrium of forces

A horizontal force $F$ acts on a frictionless trolley across a distance $s$, causing the trolley’s kinetic energy to rise from $4\,\text{J}$ to $8\,\text{J}$. If the trolley is then acted on by a force of $2F$ over a distance of $2s$, what will the initial kinetic energy of $4\,\text{J}$ increase to?

Energy conservation

A vehicle with mass $1000\,\text{kg}$ has kinetic energy of $4.5 \times 10^{5}\,\text{J}$. A total constant braking force of $6000\,\text{N}$ acts on it. What is its stopping distance?

Energy conservation

In many traditional filament lamps, for every $8\,\text{J}$ of light energy produced, as much as $92\,\text{J}$ of energy is released as thermal energy. What is the efficiency of the lamp, as the percentage of electrical energy converted to light energy?

Energy conservation

What is the expression for power in SI base units?

SI units

In an experiment designed to show Brownian motion, smoke particles in a container are illuminated by a powerful light source and viewed through a microscope. The particles appear as tiny bright specks that are moving. What causes the Brownian motion?

Atoms, nuclei and radiation

Find the ratio $\frac{10^{-3}\ \text{THz}}{10^{3}\ \text{kHz}}$?

SI units

A plate lying horizontally has an area of $0.036\,\text{m}^2$ and is positioned below the surface of a liquid with density $930\,\text{kg m}^{-3}$. The liquid pressure exerts a force of $290\,\text{N}$ on the plate. How far below the liquid surface is the plate?

Density and pressure

The graph illustrates how stress varies with strain for three wires that have identical linear dimensions but are made from different materials. Which of the following statements are correct? 1. For the same stress, the extension of P is approximately twice the extension of Q. 2. The ratio of the Young modulus of P to that of Q is approximately two. 3. When strain is less than $0.1$, R obeys Hooke’s law.

Stress and strain

The graph illustrates the effect of a force of up to $5\,\text{N}$ being applied to a spring. Assuming the spring follows Hooke’s law, what is the total extension caused by a $7\,\text{N}$ force?

Elastic and plastic behaviour

The force-extension graphs below are all drawn using the same scale. Which graph shows the deformed object with the largest amount of elastic potential energy?

Elastic and plastic behaviour

A wave that is able to be polarised must be

Polarisation

Which statement concerning electromagnetic radiation is correct?

Electromagnetic spectrum

Two sinusoidal waveforms are shown in the diagram. At time $t = 0$ the waves are in phase. The dotted line marks $t = 18\,\text{s}$. At which time is the phase difference between the two oscillations $\frac{1}{8}$ of a cycle?

Progressive waves

A sound wave is produced in a long tube that is sealed at one end. The tube’s length is changed until the sound coming from the tube reaches maximum loudness. What is the nature of the sound wave in the tube?

Stationary waves

Visible interference fringes from two light sources are seen only under particular conditions. Which condition allows visible interference fringes to be produced?

Interference

The diagram represents a pair of parallel metal plates $4.0\,\text{mm}$ apart, connected to a $9.0\,\text{V}$ battery. Find the electric field strength between the plates.

Potential difference and power

The quantities listed below may be either positive or negative. $s$ : the displacement of a particle measured along a straight line $\theta$ : the temperature reading on the Celsius scale $q$ : electric charge $V$ : the values shown on a digital voltmeter Identify which of these quantities are vectors.

Scalars and vectors

Which path indicates a possible motion of an electron in the electric field shown?

Non-uniform motion

The diagram illustrates a non-uniform electric field around a positively charged sphere and a negatively charged sphere. Four electrons, A, B, C and D, are located at different places in the field. For which electron is the direction of the force on the electron drawn correctly?

Scalars and vectors

A charge of $8.0\,\text{C}$ flows through a resistor with resistance $30\,\Omega$ at a steady rate over a time of $20\,\text{s}$. What potential difference is across the resistor?

Potential difference and power

The graph shows how the current in a lamp filament changes with potential difference (p.d.). Which statement explains the shape of this graph?

Resistance and resistivity

Cylinders X and Y are made from the same material and both conduct electricity. Their dimensions are shown. The resistance of each cylinder is found across its ends. What is the ratio $\frac{\text{resistance of X}}{\text{resistance of Y}}$?

Resistance and resistivity

A power supply with electromotive force (e.m.f.) $12\,\text{V}$ and internal resistance $2\,\Omega$ is connected in series to a load resistor. The load resistor is then adjusted from $0.5\,\Omega$ to $4\,\Omega$. Which graph illustrates how the power $P$ dissipated in the load resistor changes with the resistance of the load resistor?

Potential difference and power

Each of Kirchhoff’s laws is connected with the conservation of a physical quantity. Which physical quantities are taken to be conserved when formulating Kirchhoff’s first law and Kirchhoff’s second law?

Kirchhoff's laws

The diagram shows a potential divider circuit. By changing the position of the contact X, it can be used to produce a variable potential difference across terminals P and Q. What are the limits of this potential difference?

Potential dividers

A steady $60\,\text{V}$ d.c. supply is placed across two resistors with resistances $400\,\text{k}\Omega$ and $200\,\text{k}\Omega$. If a voltmeter with resistance $200\,\text{k}\Omega$ is connected across the $200\,\text{k}\Omega$ resistor, as in the diagram, what reading will the voltmeter show?

Practical circuits

Which statement about $\alpha$-particles is correct?

Atoms, nuclei and radiation

A micrometer is employed 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 worked out. What is the uncertainty in this difference?

Errors and uncertainties

The nucleus of the nuclide $^{241}_{94}\text{Pu}$ undergoes decay by first emitting a $\beta$-particle and then emitting an $\alpha$-particle. Which nucleus is produced?

Atoms, nuclei and radiation

A car’s speedometer has a rotating pointer. The pointer is placed a few millimetres away from a calibrated scale. What might produce a random error in the driver’s reading of the car’s speed?

Errors and uncertainties

The graph shows the velocity of an object over the first 5 seconds of its motion. What distance does the object travel in this interval?

Equations of motion

A stone with mass $m$ is released from a high building. Air resistance is significant. The acceleration of free fall is $g$. Once the stone has reached terminal velocity, which statement is correct?

Momentum and Newton's laws of motion

The graph below shows how the distance $s$ travelled by a body changes with time $t$. What does the graph show about the body’s motion?

Non-uniform motion

A golf ball is struck by a club. The graph shows how the force exerted on the ball by the club varies with time. Which quantity, during the time of contact, cannot be determined from the graph?

Momentum and Newton's laws of motion

Which set of quantities consists solely of vectors?

Scalars and vectors

An ice-hockey puck moves over a horizontal, frictionless ice-rink surface. It undergoes an inelastic collision with a wall that is at right angles to its direction of travel, and then travels back along the same path in the opposite direction. Which graph shows how the momentum $p$ varies with time $t$ for the puck?

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 car starts from rest. The graph displays the car’s momentum plotted against time. What does the gradient of the graph at a given time represent?

Momentum and Newton's laws of motion

The diagram depicts a child’s balancing toy. The wooden rod is uniform, and each ring has the same mass. Two rings are placed on peg 13 and one ring on peg 1. On which hook should a fourth ring be placed so that the rod balances?

Turning effects of forces

A ladder is in equilibrium, with one end on rough ground and the other against a rough wall. Its weight $W$ acts through the centre of gravity $G$. In addition, forces act on the ladder at $P$ and at $Q$. These forces are $P$ and $Q$ respectively. Which vector triangle shows the forces acting on the ladder?

Equilibrium of forces

A ruler with length $0.30\,\text{m}$ is balanced about a pivot at its midpoint. Two forces, each of magnitude $2.0\,\text{N}$, act in opposite directions at the ends of the ruler so that they form a couple as illustrated. In the position shown, what is the size of the torque of the couple on the ruler?

Turning effects of forces

The table’s first column lists four examples of work carried out. The second column provides further detail about the action. Which row is incorrect?

Energy conservation

The diagram shows a particle X, with kinetic energy $E_k$, just before it collides with a particle Y that is at rest. The two particles have equal mass. Following the collision, X and Y continue moving together as one larger particle. How much kinetic energy is lost in the collision?

Linear momentum and its conservation

An electric motor is needed to provide $120\,\text{W}$ of mechanical output power. The motor’s efficiency is $80\%$. Which row is correct?

Potential difference and power

A mass $m$ is located in space within a uniform gravitational field. As the mass undergoes a displacement $x$ from P to Q, it loses potential energy $E$. Which row correctly states both the magnitude and the direction of the acceleration due to gravity in this field?

Gravitational potential energy and kinetic energy

Which statement that uses prefixes of the base unit metre (m) is incorrect?

SI units

A trolley moves from P to Q along a track. By the time it reaches Q, its potential energy is $50\,\text{kJ}$ lower than it was at P. At P, the trolley has a kinetic energy of $5\,\text{kJ}$. As it travels between P and Q, the trolley does $10\,\text{kJ}$ of work against friction. Determine the kinetic energy of the trolley at Q?

Energy conservation

A steel wire of a certain length is used to determine the Young modulus of steel, and the result is found to be $E$. A second experiment is then performed with a wire of the same steel, but with half the length and half the diameter. What value is obtained for the Young modulus in this second experiment?

Stress and strain

A rubber band is stretched and then allowed to return to its original length. The diagram illustrates the force-extension graph for this process. As the force increases, the curve traces the path OPQ to extension $e$. As the force decreases, the curve follows the path QRO to go back to zero extension. The area marked $X$ lies between the curves OPQ and QRO. The area marked $Y$ is enclosed by the curve QRO and the horizontal axis. Which statement about the process is correct?

Elastic and plastic behaviour

Pollen grains are mixed into a liquid and brightly illuminated. Under a microscope, they are observed to move randomly all the time. What causes this?

Atoms, nuclei and radiation

Why does the pressure rise when a sealed container of gas is heated?

Density and pressure

A metal cube with side $l$ is held in a vice and undergoes elastic compression due to two opposing forces $F$. What is the relationship between $\Delta l$, the amount of compression, and $l$?

Stress and strain

To describe how a spring behaves, the spring constant is used. Several different loads are applied so that the spring extends by different amounts. Which quantities are needed to determine the spring constant?

Elastic and plastic behaviour

The diagram gives a plan view of a double-slit interference setup. $L$ is a monochromatic light source with a vertical filament. $B$ is a barrier containing two thin vertical slits and $S$ is a screen on which interference fringes are produced. The intensity is $I$ at a point on the screen where the centre of the fringe pattern is formed. What is the intensity, at that same point, when one slit is blocked?

Interference

$P$ is a source that emits infra-red radiation, while $Q$ is a source that emits ultra-violet radiation. The numbers in the table are proposed wavelength values for the radiation given off by $P$ and $Q$. Which row is correct?

Electromagnetic spectrum

Coherent waves are generated at $P$ and at $Q$ and spread outwards in every direction. The line $RS$ lies midway between $P$ and $Q$ and is at right angles to the line joining $P$ and $Q$. The distance $RS$ is much larger than the distance $PQ$. On which line, or lines, can an interference pattern be seen?

Interference

The Young modulus of the material in a wire is to be determined. The Young modulus $E$ is given by the equation $E = \frac{4Fl}{\pi d^{2} x}$. A known force is applied to stretch the wire and the following measurements are taken. Which measurement contributes the greatest effect to the uncertainty in the calculated Young modulus?

Stress and strain

Travelling waves with wavelength $20\,\text{cm}$ are set up in the air columns of a closed pipe P and an open pipe Q. The pipe lengths are shown. In which pipe or pipes do stationary waves form?

Stationary waves

The diagram depicts an insulating rod with equal and opposite point charges at its two ends. An electric field of strength $E$ acts on the rod downward. Which row is correct?

Turning effects of forces

A pair of horizontal parallel plate conductors is separated by an air gap of $5.0\,\text{mm}$. The lower plate is earthed, while the upper plate is held at $+50\,\text{V}$. What is the electric field strength $E$ at a point halfway between the plates?

Potential difference and power

An atomic nucleus emits a $\beta$-particle. How do the proton number and nucleon number of the nucleus change as a result?

Atoms, nuclei and radiation

Which statement is incorrect?

Errors and uncertainties

Which of the following statements about electrical resistivity is correct?

Resistance and resistivity

A cell, two resistors with the same resistance, and an ammeter are used to make four circuits. The resistors are the only components in the circuits that provide resistance. In which circuit will the ammeter give the largest reading?

Practical circuits

Three resistors with resistances $R$, $2R$ and $3R$ are joined in parallel. Using $I$ to stand for the current in the resistor of resistance $R$, which row shows the relationships between the currents in the resistors?

Electric current

A cell with e.m.f. $E$ and internal resistance $r$ is connected in series with a switch $S$ and an external resistor having resistance $R$. The potential difference between $P$ and $Q$ is $V$. After $S$ is closed,

Practical circuits

Which equation linking several of the terms listed below is correct? potential difference (p.d.) $V$ current $I$ resistance $R$ charge $Q$ energy $E$ power $P$ time $t$

Potential difference and power

An Olympic athlete with a mass of $80\,\text{kg}$ is taking part in a $100\,\text{m}$ race. What is the most suitable estimate of his mean kinetic energy during the race?

Gravitational potential energy and kinetic energy

The diagram illustrates a potential divider circuit used to produce a variable output p.d. Which row states the range of output p.d. that can be obtained?

Potential dividers

A cylindrical tube that rolls down a slope with inclination $\theta$ travels a distance $L$ in a time $T$. These quantities are connected by $L\left(3 + \frac{a^{2}}{P}\right) = QT^{2}\sin \theta$. In this expression, $a$ is the tube’s internal radius, and $P$ and $Q$ are constants. Which line gives the correct units for $P$ and $Q$?

SI units

A tennis ball is dropped from rest from the roof of a high building. Which graph most accurately shows how the acceleration $a$ of the ball changes with time $t$ as it falls, if air resistance cannot be ignored?

Non-uniform motion

A ball is let go from rest on a smooth incline $XY$. It travels down the incline, continues over the smooth horizontal section $YZ$ and rebounds inelastically at $Z$. It then returns to $Y$ and briefly comes to rest at some point on $XY$. Which velocity-time graph shows the motion of the ball?

Equations of motion

An object is falling through a uniform gravitational field and experiences air resistance. The air resistance rises until terminal velocity is attained. Which factor has no effect on its terminal velocity?

Equilibrium of forces

A boy throws a ball straight up. The ball reaches a greatest height, where it is briefly at rest, and then returns to his hands. Which row shows the ball’s acceleration during the different parts of its motion? (Take upward direction as positive. Ignore air resistance.)

Equations of motion