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Leaving Cert Physics: Work energy and power

How often Work energy and power comes up on the Physics papers, every year it was asked, and questions to try.

HL Asked on 8 of the last 10 Higher Level papers, most recently in 2026. most years

OL Asked on 9 of the last 10 Ordinary Level papers, most recently in 2026. banker

June 2027 is the first exam on the new Physics course. These come from the 2016–2026 papers, so read them as a guide.

Work energy and power, Higher Level(7 marks)

Quick ones on Work energy and power.

(a)SI unit of work?
  1. Newton (N)
  2. Joule (J)
  3. Watt (W)
(b)Define power.
  1. Force multiplied by distance
  2. The total work done by a machine
  3. The rate at which work is done
(c)Kinetic energy of a 2.0 kg mass moving at 10 m s⁻¹?
  1. 100 J
  2. 20 J
  3. 200 J
Show the answers

(a) Joule (J)

(b) The rate at which work is done

(c) 100 J

Your turn: Higher Level questions on Work energy and power.

Higher Level

Asked on 8 of the last 10 Higher Level papers, most recently in 2026. most years

Every paper, year by year

YearWhere it came up
2026Q6(f)
2025Not asked
2024Q14(a)
2023Q13
2022Not asked
2021Q7
2019Q12(a)
2018Q6
2017Q6
2016Q5(a), Q7

Links open the State Examinations Commission’s paper for that year.

More Work energy and power questions

Work energy and power, 2 marks

Define the work done by a constant force.

  1. The force divided by the time for which the force acts
  2. The mass multiplied by the distance moved in the direction of the force
  3. The force multiplied by the displacement in the direction of the force
Show the answer

The force multiplied by the displacement in the direction of the force

W = Fs, measured in joules. A force at right angles to the motion (like the normal force on a sliding box) does no work.

Work energy and power, 3 marks

A trolley is released from rest at the top of a smooth ramp 0.80 m high. Its speed at the bottom (g = 9.8 m s⁻²)?

  1. 7.8 m s⁻¹
  2. 4.0 m s⁻¹
  3. 15.7 m s⁻¹
Show the answer

4.0 m s⁻¹

mgh = ½mv², so v = √(2gh) = √(2 × 9.8 × 0.80) = √15.7 = 4.0 m s⁻¹. 15.7 is v², not v. Mass cancels out.

Work energy and power, 2 marks

A machine does 360 J of useful work for every 480 J of energy supplied. What is its efficiency?

  1. 75%
  2. 133%
  3. 25%
Show the answer

75%

Efficiency = useful output ÷ input × 100 = 360 ÷ 480 × 100 = 75%. It can never exceed 100%; 25% is the fraction wasted.

Ordinary Level

Asked on 9 of the last 10 Ordinary Level papers, most recently in 2026. banker

Every paper, year by year

YearWhere it came up
2026Q6(c), Q6(d)
2025Q11, Q14(a)
2024Q7
2023Q6(d), Q7
2022Q6(b), Q14(a)
2021Not asked
2019Q5(e), Q12(a)
2018Q5(c), Q6
2017Q6
2016Q5(b), Q5(c), Q12(a)

Links open the State Examinations Commission’s paper for that year.

More Work energy and power questions

Work energy and power, 3 marks

State the principle of conservation of energy.

  1. Energy is always lost when it changes from one form to another
  2. The total energy of the universe keeps increasing as time goes on
  3. Energy cannot be created or destroyed, only changed from one form to another
Show the answer

Energy cannot be created or destroyed, only changed from one form to another

Energy is never lost, only converted. Energy that seems lost has usually been changed to heat or sound.

Work energy and power, 3 marks

A motor takes in 500 J and does 400 J of useful work. Its efficiency?

  1. 20%
  2. 80%
  3. 125%
Show the answer

80%

Efficiency = useful output ÷ input × 100 = 400 ÷ 500 × 100 = 80%. No machine can be more than 100% efficient.

Work energy and power, 2 marks

Define work.

  1. Force multiplied by the distance moved in the direction of the force
  2. Force divided by the distance moved in the direction of the force
  3. Mass multiplied by the velocity of the body
Show the answer

Force multiplied by the distance moved in the direction of the force

W = F × s, unit the joule (J). Mass × velocity is momentum.

Other Physics topics

All of Leaving Cert Physics