Physics

What force pulls objects towards the Earth?

• ATension
• BFriction
• CGravity✓
• DMagnetism

Answer: Gravity is the force of attraction that pulls masses towards each other, e.g. towards Earth.

What is the unit of force?

• ANewton✓
• BJoule
• CKilogram
• DWatt

Answer: Force is measured in newtons (N).

Friction is a force that:

• AMakes a moving object travel faster
• BMakes heavy objects float in water
• CPulls objects down towards the Earth
• DOpposes motion between surfaces✓

Answer: Friction acts against movement where two surfaces meet, slowing things down.

Which of these is a source of renewable energy?

• AWind✓
• BNatural gas
• COil
• DCoal

Answer: Wind is renewable — it won't run out. Coal, oil and gas are non-renewable fossil fuels.

In a simple electric circuit, what provides the energy?

• AThe cell or battery✓
• BThe bulb
• CThe wires or the connecting clips
• DThe switch

Answer: The cell or battery is the source of electrical energy that pushes the current.

A switch in a circuit is used to:

• AStore up energy to use later on
• BTurn the current on or off✓
• CWork out how much voltage there is
• DLight up or buzz when switched on

Answer: A switch opens or closes the circuit to stop or allow the flow of current.

Light travels:

• ABackwards
• BSlower than sound
• COnly in water
• DIn straight lines✓

Answer: Light travels in straight lines until it hits something that reflects or refracts it.

We see most objects because they:

• AProduce their own light
• BAbsorb the light
• CGlow in the dark
• DReflect light into our eyes✓

Answer: Most objects don't make light; we see them when they reflect light into our eyes.

Sound is caused by:

• AHeat only
• BGravity
• CVibrations✓
• DLight waves

Answer: Sound is made by vibrating objects, which create sound waves that travel through a medium.

Sound cannot travel through:

• AWater (in a pool or a bath)
• BAir
• CSolid walls and wooden doors
• DA vacuum (empty space)✓

Answer: Sound needs particles to travel; in a vacuum there are none, so sound cannot pass.

Which planet is closest to the Sun?

• AEarth
• BMercury✓
• CVenus
• DMars

Answer: Mercury is the closest planet to the Sun in our Solar System.

What causes day and night on Earth?

• AThe Earth orbiting the Sun once a year
• BClouds blocking the Sun
• CThe Moon's phases
• DThe Earth spinning on its axis✓

Answer: Earth rotates on its axis once a day; the side facing the Sun has day, the other has night.

How long does the Earth take to orbit the Sun once?

• AOne month
• BOne week
• COne year✓
• DOne day

Answer: Earth takes about 365¼ days — one year — to orbit the Sun.

The energy stored in food and fuels is called:

• AElectrical energy
• BGravitational energy
• CChemical energy✓
• DLight, sound or heat energy

Answer: Food and fuels store chemical energy, which can be released by reactions such as respiration or burning.

A magnet will attract which material?

• AWood
• BIron✓
• CPlastic
• DGlass

Answer: Magnetic materials include iron, steel, nickel and cobalt; plastic, wood and glass are not magnetic.

When two forces on an object are equal and opposite, the forces are:

• AUnbalanced
• BRemoved
• CBalanced✓
• DMagnetic

Answer: Equal and opposite forces are balanced, so the object stays still or moves at a steady speed.

A cyclist travels 900 m in 60 seconds. What is her average speed?

• A54,000 m/s
• B0.07 m/s
• C840 m/s
• D15 m/s✓

Answer: Speed is distance divided by time: 900 ÷ 60 = 15 m/s. Multiplying the two figures gives 54,000 and subtracting them gives 840, and neither of those is a speed.

On a distance-time graph, what does a horizontal flat line tell you about the object?

• AIt is speeding up
• BIt is stationary✓
• CIt is moving at a steady speed
• DIt is returning to the start

Answer: A flat line means the distance from the starting point is not changing as time passes, so the object is not moving. A straight sloping line is what shows a steady speed.

A car is driven along a straight road and the forward force from the engine is larger than the total backward force. What happens to the car?

• AIt travels at a constant speed
• BIt speeds up✓
• CIt slows down
• DIt stays where it is

Answer: Unbalanced forces make an object accelerate in the direction of the larger force, so a bigger forward force makes the car speed up. Balanced forces are what produce a constant speed.

A spring stretches by 4 cm when a 2 N weight hangs from it. If it obeys Hooke's law, how far will it stretch with a 5 N weight?

• A7 cm
• B10 cm✓
• C20 cm
• D2.5 cm

Answer: Extension is directly proportional to the force, so each 1 N produces 2 cm of stretch and 5 N produces 5 × 2 = 10 cm. Adding the extra 3 N on as 3 cm gives 7 cm and ignores the proportion.

A force of 200 N presses on an area of 0.5 m². What is the pressure?

• A100 N/m²
• B400 N/m²✓
• C0.0025 N/m²
• D200 N/m²

Answer: Pressure is force divided by area: 200 ÷ 0.5 = 400 N/m², which is 400 pascals. Multiplying the two figures gives 100, and dividing the area by the force gives 0.0025.

A spanner is 0.3 m long and a force of 20 N is applied at right angles to its end. What is the moment about the bolt?

• A20.3 Nm
• B66.7 Nm
• C0.015 Nm
• D6 Nm✓

Answer: A moment is the force multiplied by the perpendicular distance from the pivot: 20 × 0.3 = 6 Nm. Dividing the force by the distance gives 66.7, which is the calculation upside down.

A catapult is pulled back ready to fire. Which energy store has been filled?

• AThe elastic potential store✓
• BThe thermal store
• CThe chemical store
• DThe gravitational potential store

Answer: Stretching or squashing an elastic object fills its elastic potential store, and that energy is transferred to the kinetic store of whatever is fired when the catapult is released.

An electric heater is rated at 2 kW and runs for 3 hours. If electricity costs 30p per kilowatt-hour, what does that cost?

• A60p
• B90p
• C£1.80✓
• D£6.00

Answer: Energy used is power multiplied by time: 2 × 3 = 6 kilowatt-hours. At 30p each that comes to 180p, or £1.80. Leaving the time out of the calculation gives 60p.

A metal spoon left standing in a hot drink soon feels hot at the handle. Which process carries the energy along the spoon?

• AConvection
• BRadiation
• CConduction✓
• DEvaporation

Answer: In a solid metal the particles are packed closely and free electrons carry energy rapidly through the material, which is conduction. Convection needs a fluid that can flow, and radiation travels as infrared waves with no material at all.

How could you make an electromagnet stronger without changing the power supply?

• AWind more turns of wire onto the coil✓
• BFit a plastic core in place of the iron one
• CUse a shorter length of thinner wire
• DReverse the direction of the current

Answer: Adding more turns of wire increases the magnetic field the coil produces, so the electromagnet becomes stronger. Reversing the current only swaps the poles round, and a plastic core is far weaker than an iron one.

An electric bell rings inside a sealed glass jar. As the air is pumped out, the sound fades away. What does this show?

• ASound needs a material to travel through✓
• BSound travels faster in a vacuum
• CThe bell has stopped vibrating
• DSound is a type of light wave

Answer: Sound is a vibration passed on from particle to particle, so once the particles have been removed there is nothing left to carry it. Light still crosses the vacuum, which is why the bell can still be seen moving.

A ray of light strikes a plane mirror at an angle of incidence of 30°. What is the angle of reflection?

• A60°
• B30°✓
• C90°
• D150°

Answer: The law of reflection says the angle of reflection is equal to the angle of incidence, with both measured from the normal, so the reflected ray leaves at 30°.

A ray of light passes at an angle from air into a glass block. What happens to it?

• AIt speeds up and bends away from the normal
• BIt slows down and bends towards the normal✓
• CIt slows down and bends away from the normal
• DIt keeps the same speed and carries straight on

Answer: Glass is optically denser than air, so the light slows down as it enters and the ray bends towards the normal. It bends away from the normal again as it leaves the block and speeds back up.

Three identical bulbs are connected in series with one cell. What is true about the current in that circuit?

• AIt is largest at the bulb nearest the cell
• BIt is the same at every point in the circuit✓
• CIt is used up as it passes through each bulb
• DIt is shared out between the three bulbs

Answer: Current is a flow of charge, and in a single loop the same charge passes through every component, so an ammeter reads the same wherever it is placed. Energy is transferred at each bulb, but the current itself is not used up.

How should a voltmeter be connected to measure the potential difference across a lamp?

• AIn parallel, across the lamp✓
• BIn series, in the main circuit loop
• CIn series, right next to the cell
• DAcross the two terminals of the switch

Answer: A voltmeter compares the energy carried by the charge on either side of a component, so it must be connected in parallel across that component. The ammeter is the meter that goes in series.

Why does the UK have warmer summers than winters?

• AThe Earth's orbit brings it closer to the Sun in summer
• BThe Sun gives out more energy during the summer
• CThe Earth's tilt raises the Sun higher in the sky✓
• DThe Earth spins more slowly in the summer

Answer: The Earth's axis is tilted, so in summer the northern hemisphere leans towards the Sun. Sunlight then strikes the ground more directly and the days are longer, which is what makes it warmer. The distance to the Sun barely changes, and the daily spin that gives day and night keeps the same rate all year.