IGCSE Physics 0625 — Topic 1: Motion, Forces and Energy — Paper 2 (MCQ) Cambridge Challenge 2

Question 1

A student needs the thickness of a single sheet of paper, which is far too thin to measure directly with a ruler.

She measures a stack of 100 identical sheets as 1.20 cm thick. What is the thickness of one sheet, and why is this method accurate?

A0.12 mm; measuring many sheets together makes the ruler’s reading error a much smaller fraction of the measured length B0.012 mm; measuring many sheets together makes the ruler’s reading error a much smaller fraction of the measured length C0.12 mm; stacking the sheets presses them together, which makes each individual sheet measurably thinner and easier to read D1.2 mm; the thickness of one sheet is found by dividing the height of the stack by the ten sheets nearest the ruler

Question 2

A student times 25 complete oscillations of a pendulum at 44.0 s, using a digital stopwatch she starts and stops by hand.

What is the period, and what is the main reason for timing 25 oscillations rather than one?

A1.76 s; her reaction-time error occurs only twice however many swings are timed, so its share of each measured period shrinks B0.57 s; the period is the number of oscillations divided by the total time that the student measured on the stopwatch C44.0 s; the period of a pendulum is defined as the time for the complete set of oscillations that were counted D1.76 s; a digital stopwatch only becomes accurate once it has been running continuously for more than about half a minute

Question 3

Which list contains ONLY vector quantities?

AVelocity, acceleration, force, momentum BAcceleration, momentum, time, weight CSpeed, distance, energy, temperature DVelocity, speed, force, mass

Question 4

A cyclist rides 600 m up a hill at a steady 6.0 m/s, then back down the same 600 m at a steady 12 m/s.

What is her average speed for the whole journey?

A9.0 m/s B8.0 m/s C10 m/s D7.2 m/s

Question 5

A distance-time graph is drawn for a runner.

Which feature of the graph gives the runner’s speed at any moment, and what does a curve of steadily increasing steepness show?

AThe gradient gives the speed; increasing steepness shows the runner is slowing down steadily BThe gradient gives the speed; increasing steepness shows the runner is accelerating CThe height of the graph gives the speed; increasing steepness shows the runner is moving backwards DThe area under the graph gives the speed; increasing steepness shows the runner is accelerating

Question 6

A tram starts from rest and speeds up uniformly to 12 m/s in 6.0 s, then holds that speed for a further 4.0 s.

How far does it travel in the whole 10 s?

A132 m B120 m C84 m D48 m

Question 7

A metro train accelerates uniformly from 18 m/s to 30 m/s in 8.0 s.

What is its acceleration?

A3.8 m/s² B6.0 m/s² C2.3 m/s² D1.5 m/s²

Question 8

A lorry’s journey is recorded on a speed-time graph. Between points X and Y the line slopes downwards from 24 m/s to 6 m/s; the line is straight.

What is happening between X and Y?

AThe lorry is slowing down at a rate that keeps changing, because its speed is different at every moment BThe lorry is stationary between the two points, because the line eventually approaches the time axis CThe lorry is moving backwards, because a downward slope on a motion graph always shows reversed motion DThe lorry is slowing down at a constant rate, while continuing to move forwards the whole time

Question 9

A raindrop falls from a high cloud. After several seconds it reaches terminal velocity.

Which statement describes the forces on the raindrop and its motion at terminal velocity?

AAir resistance has grown until it equals the raindrop’s weight, so the resultant force is zero and the speed is constant BBoth forces have fallen to zero at terminal velocity, which is why the raindrop no longer accelerates downwards CAir resistance has become greater than the raindrop’s weight, which is what finally stops the drop from accelerating DThe raindrop’s weight has decreased during the fall until it equals the air resistance acting on the drop

Question 10

A stone is dropped from rest off a high bridge and falls freely for 2.0 s. Air resistance is negligible and g = 9.8 m/s².

How far does the stone fall in this time?

A9.8 m B39.2 m C4.9 m D19.6 m

Question 11

A space probe of mass 4.0 kg is sent from Earth to Jupiter, where the gravitational field strength is 25 N/kg (Earth: 9.8 N/kg).

What are its mass and weight on Jupiter?

AMass 10 kg; weight 100 N BMass 1.6 kg; weight 39 N CMass 4.0 kg; weight 100 N DMass 4.0 kg; weight 39 N

Question 12

A pebble has a mass of 135 g. When lowered into a measuring cylinder containing 80 cm³ of water, the level rises to 130 cm³.

What is the density of the pebble?

A0.37 g/cm³ B1.0 g/cm³ C1.7 g/cm³ D2.7 g/cm³

Question 13

Four blocks are measured. Block A: mass 500 g, volume 400 cm³. Block B: mass 270 g, volume 300 cm³. Block C: mass 1200 g, volume 1000 cm³. Block D: mass 30 g, volume 40 cm³.

Water has density 1.0 g/cm³. Which blocks float in water?

AA and C only BB and D only CD only DA, B and D

Question 14

The density of aluminium is 2.7 g/cm³.

What is this density in kg/m³?

A2700 kg/m³ B0.0027 kg/m³ C270 000 kg/m³ D2.7 kg/m³

Question 15

A sealed metal box has a mass of 240 g and a total volume of 400 cm³. The metal it is made from has a density of 8.0 g/cm³, but the box floats in water (density 1.0 g/cm³).

How can a metal box float?

AThe box’s AVERAGE density is 0.6 g/cm³, because the air-filled space inside it counts towards its volume but adds almost no mass BThe box floats only because of the surface tension of the water, which can support any object that is placed down gently CThe water pushes harder on metal than on other materials, and this extra upward push is what supports the floating box DThe metal’s density falls below that of water as soon as the metal is formed into the thin walls of a hollow shape

Question 16

A spring is loaded and its extension recorded: 2.0 N gives 4.0 cm; 4.0 N gives 8.0 cm; 6.0 N gives 12.0 cm; 8.0 N gives 18.0 cm.

What do the results show?

AExtension is proportional to load up to 6.0 N, but between 6.0 N and 8.0 N the limit of proportionality is passed BExtension is proportional to load over the whole range that was tested, from 2.0 N right up to the 8.0 N load CThe spring obeys the proportionality law only for the very first reading, and every later reading breaks the pattern DThe results must contain a measurement error, because a spring always stretches in proportion to the load applied

Question 17

A motorboat of mass 750 kg experiences a forward thrust of 4000 N from its propeller and a total drag of 2500 N from the water and air.

What is its acceleration?

A3.3 m/s² B2.0 m/s² C8.7 m/s² D5.3 m/s²

Question 18

A resultant force of 60 N acts on a supermarket trolley and gives it an acceleration of 2.4 m/s².

What is the mass of the trolley?

A62 kg B144 kg C0.04 kg D25 kg

Question 19

A delivery van travels along a straight, level road at a constant 20 m/s.

What is known about the forces acting on the van?

AThere is a constant forward resultant force on the van, which is needed to maintain its constant speed BThe resultant force on the van is zero: the driving force exactly balances the total resistive force CNo forces at all act on the van while its speed is not changing in any way DThe driving force is slightly larger than the resistive forces, with the excess maintaining the motion

Question 20

A heavy crate is pushed across a rough floor at a constant speed by a horizontal force of 180 N.

What is the friction force on the crate, and what happens the moment the push is removed?

AFriction is less than 180 N; the difference between the forces is what keeps the crate moving forwards BFriction is zero while the crate moves; friction only acts on objects that are stationary on a surface CFriction is 180 N backwards; without the push the unbalanced friction decelerates the crate to rest DFriction is 180 N backwards; without the push the crate continues at a constant speed on the rough floor

Question 21

A car travels round a bend at constant speed. The driver then takes the same bend on an icy day, when friction between the tyres and road is greatly reduced.

Why is the icy bend dangerous?

AFriction on ice acts in the opposite direction, pushing the car outwards away from the centre of the bend BIce increases the car’s momentum, and a car with more momentum always needs a larger distance in which to turn CThe cold air on an icy day increases the drag on the car, making the engine work harder and the car harder to steer DFriction supplies the sideways force towards the centre of the bend that continually changes the car’s direction; with too little friction the car continues in nearly a straight line

Question 22

A gardener lifts the loaded end of a wheelbarrow. The load of 300 N acts 0.50 m from the wheel’s axle, and the gardener lifts the handles 1.5 m from the axle.

What upward force must the gardener apply to just balance the load?

A300 N B900 N C100 N D150 N

Question 23

A non-uniform metre rule is pivoted at its 40 cm mark and balances horizontally when a 2.0 N weight hangs from the 20 cm mark. The rule’s own weight acts at its 50 cm mark.

What is the weight of the rule?

A1.0 N B8.0 N C2.0 N D4.0 N

Question 24

A ladder leans against a wall, at rest.

Which TWO conditions must BOTH be satisfied for the ladder to remain in equilibrium?

AThe forces on it must all be vertical, and the total upward force must be twice the total downward force BThe resultant force on it must be zero; once that is true, no separate condition on moments is ever needed CThe resultant force on it must be zero, and the resultant moment about any point must also be zero DThe resultant moment must be zero, and every individual force acting on the ladder must also be zero

Question 25

An empty double-decker bus is stable, but the same bus with passengers standing on the upper deck and an empty lower deck tips over at a smaller angle of lean.

Why?

AThe passengers increase the total weight of the bus, and heavier objects of every shape always tip over at smaller angles BThe standing passengers raise the bus’s centre of gravity, so a smaller lean moves its weight’s line of action outside the wheelbase CThe passengers raise the bus’s centre of gravity, which makes the bus lighter and therefore much easier to push over DThe moving bus gains momentum from the passengers, and extra momentum always makes any vehicle less stable

Question 26

A 0.80 kg trolley moving at 3.0 m/s collides with a stationary 1.2 kg trolley, and the two stick together.

What is their common speed immediately after the collision?

A1.5 m/s B2.0 m/s C1.2 m/s D3.0 m/s

Question 27

In a tennis serve, a 0.060 kg ball leaves the racket at 50 m/s having been struck from rest. The ball and strings are in contact for 0.020 s.

What average force does the racket exert on the ball?

A0.06 N B150 N C3.0 N D60 N

Question 28

A stationary cannon of mass 500 kg fires a 2.0 kg cannonball horizontally at 150 m/s.

What happens to the cannon?

AIt recoils backwards at 150 m/s, because both objects must always gain exactly equal speeds BIt recoils backwards at 0.60 m/s, so that the total momentum of cannon and ball remains zero CIt remains exactly stationary, because the cannon’s much larger mass completely absorbs the recoil DIt moves slowly forwards behind the ball, dragged along by the pressure of the expanding gases

Question 29

A car of mass 800 kg travels at 15 m/s.

What is its kinetic energy?

A90 kJ B180 kJ C6.0 kJ D12 kJ

Question 30

A pendulum bob is pulled aside so that it is raised 0.20 m above its lowest point, and released from rest. Air resistance is negligible and g = 9.8 m/s².

What is the bob’s speed at the lowest point?

A1.4 m/s B3.9 m/s C0.98 m/s D2.0 m/s

Question 31

A sledge is dragged 40 m across level snow against a constant friction force of 250 N, at constant speed.

How much work is done against friction, and what becomes of this energy?

A10 kJ, stored as kinetic energy that the sledge keeps for as long as it continues to move B6.3 kJ, transferred to the internal chemical energy of the material of the sledge’s runners C10 kJ, stored as gravitational potential energy even though the snowfield is completely level D10 kJ, transferred to thermal energy that raises the temperature of the runners and the snow

Question 32

A student of mass 50 kg runs up a flight of stairs of vertical height 4.0 m in 5.0 s (g = 9.8 N/kg).

What useful power does she develop against gravity?

A1960 W B98 W C390 W D40 W

Question 33

An electric kettle transfers 2000 J of energy, of which 500 J ends up heating the kitchen air instead of the water.

What is the kettle’s efficiency?

A80% B25% C75% D133%

Question 34

Most of the Earth’s energy resources can be traced back to the Sun.

Which energy resource does NOT derive its energy from the Sun?

AThe wind that turns wind turbines BThe fossil fuels burned in conventional power stations CNuclear fuel used in power stations DThe flowing rivers that supply hydroelectric dams

Question 35

A car’s speed increases from v to 2v.

What happens to its kinetic energy, and roughly what does this imply for the distance needed to brake to rest from the higher speed?

AThe kinetic energy becomes four times larger, but the braking distance stays the same because the brakes are unchanged BThe kinetic energy becomes twice as large, but the braking distance becomes four times longer than before CThe kinetic energy becomes twice as large, so the braking distance is roughly twice as long as before DThe kinetic energy becomes four times larger, so the braking distance is roughly four times longer

Question 36

A toboggan and rider start from rest at the top of a slope, 1200 J of gravitational potential energy above the bottom. At the bottom their kinetic energy is 900 J.

What does the missing 300 J represent?

AGravitational potential energy still stored in the toboggan at the bottom, waiting to be released as extra speed later BEnergy destroyed by the friction between the toboggan’s runners and the surface of the snow on the way down CEnergy transferred to thermal energy by friction and air resistance during the descent — the total energy is still accounted for DA measurement error, because by the principle of conservation the kinetic energy at the bottom had to be exactly 1200 J

Question 37

A packing case weighs 600 N and its base measures 0.50 m by 0.40 m.

What pressure does it exert on the floor when standing on its base?

A120 Pa B3000 Pa C1200 Pa D300 Pa

Question 38

A tractor designed for soft ground is fitted with very wide tyres.

Why?

AThe wide tyres increase the contact area, so the tractor’s weight produces a smaller pressure and the tyres sink less into the ground BThe wide tyres reduce the total weight of the tractor, which is what prevents it from sinking into soft ground CThe wide tyres raise the tractor higher above the ground, keeping its weight further away from the soft surface DThe wide tyres decrease the contact area, so the tractor’s weight produces a larger pressure and better grips the ground

Question 39

A tank on a farm is filled with olive oil of density 850 kg/m³ to a depth of 2.0 m (g = 9.8 N/kg).

What is the pressure due to the oil at the bottom of the tank?

A8.3 kPa B16.7 kPa C1.7 kPa D19.6 kPa

Question 40

A small hole is made in the side of a water tank near its base, and another identical hole at the same depth on the opposite side. Water jets out of both holes equally.

What does this demonstrate about pressure in a liquid?

AAt a given depth the pressure acts equally in all directions, and it increases with depth below the surface BPressure in a liquid acts only vertically downwards, which is why the water must first fall before leaving each hole CPressure is the same at every point throughout a liquid, whatever the depth of the point below the surface DPressure in a liquid depends on the total volume of water stored, so wider tanks push water out much further

Paper 2 — Multiple Choice

Section A: Measurement and Motion

Section B: Mass, Weight and Density

Section C: Forces, Moments and Momentum

Section D: Energy, Work and Power

Section E: Pressure