GCSE Physics Work and power questions by topic

Complete the sentences about work and power.

1. (a)Work done = force × …[1]
2. (b)Work done is measured in …[1]
3. (c)Power = work done ÷ …[1]
4. (d)Power is measured in …[1]

A student pushes a trolley with a horizontal force of 250 N for 4.0 m.

1. (a)State the equation linking work done, force and distance.[1]
2. (b)Calculate the work done.[2]
3. (c)Name the store that receives most of this energy when the floor is rough.[1]

A spring hangs from a clamp with a ruler beside it. A 2.0 N load stretches it 8.0 cm.

1. (a)State what is meant by the extension of the spring.[1]
2. (b)Convert 8.0 cm into metres.[1]
3. (c)Calculate the spring constant in N/m.[2]

A motor lifts a load and transfers 9 600 J of energy in 16 s.

1. (a)Write down the equation linking power, work done and time.[1]
2. (b)Calculate the power of the motor.[2]

A spring obeys Hooke’s law. A force of 6.0 N stretches it by 0.030 m.

1. (a)Calculate the spring constant, in N/m.[2]
2. (b)Calculate the extension produced by a 9.0 N force.[2]
3. (c)State one assumption you made in part (b).[1]

A 70 kg climber climbs 8.0 m up a rock face in 20 s (g = 9.8 N/kg).

1. (a)Calculate her weight.[1]
2. (b)Calculate the work she does against gravity.[2]
3. (c)Calculate her useful power output.[2]
4. (d)Her actual power output is higher than the answer to (c). Give one reason.[1]

A student investigates how the extension of a spring depends on the force applied.

1. (a)Describe how she should obtain measurements for one force, and how the extension is calculated.[3]
2. (b)State which quantities she plots on each axis, and what the gradient of the straight portion represents.[2]
3. (c)Give one safety precaution.[1]

A spring with spring constant 200 N/m is stretched elastically by 0.30 m.

1. (a)Calculate the force needed.[2]
2. (b)Calculate the elastic potential energy stored.[3]

Two students stretch identical springs. Student A extends hers 0.10 m; Student B extends hers 0.20 m (both within the Hooke region).

1. (a)Compare the forces needed for the two stretches.[2]
2. (b)Compare the elastic energy stored in the two springs.[3]
3. (c)Name the graph feature that represents the extra energy Student B stored.[1]

A crane lifts a 500 kg container 12 m at steady speed in 30 s (g = 9.8 N/kg).

1. (a)Calculate the weight of the container.[2]
2. (b)Calculate the useful work done by the crane.[2]
3. (c)Calculate the useful power of the crane.[2]
4. (d)The crane’s motor draws more power than the answer to (c). Explain why.[2]

A student hangs masses on a spring and records: 1.0 N → 0.020 m, 2.0 N → 0.040 m, 3.0 N → 0.060 m, 4.0 N → 0.085 m.

1. (a)Explain which readings obey Hooke’s law and which do not.[3]
2. (b)Calculate the spring constant from the linear region.[2]
3. (c)Calculate the energy stored at 3.0 N extension.[2]

A catapult elastic (k = 100 N/m) is stretched 0.20 m and launches a 0.020 kg ball horizontally.

1. (a)Calculate the force applied at full stretch.[2]
2. (b)Calculate the elastic energy stored at full stretch.[2]
3. (c)Assuming all the stored energy transfers to the ball, calculate its launch speed.[3]
4. (d)State one reason the ball’s actual speed is lower.[1]