Who this is for: Cambridge IGCSE Physics (0625) students who want Energy, Work and Power — using E_k = ½mv², E_p = mgh, W = Fs and P = W/t — to become a reliable source of marks instead of a set of formulas they mix up under pressure.
What query it owns: how to understand and revise Energy, Work and Power in Cambridge IGCSE Physics.
Why this is safe: this page owns the Energy, Work and Power revision-guide angle, while Tutopiya’s Energy, Work and Power subtopic page owns the learning resource and the free Energy, Work and Power quiz owns the practice.

Energy, Work and Power is one of the highest-yield areas in Cambridge IGCSE Physics (0625). Examiners expect you to calculate kinetic and gravitational potential energy, relate work done to energy transferred, find power, and interpret efficiency. This guide explains the key formulas, energy transfer pathways, the question types that actually appear, and where to practise each skill.

Key takeaways

• Kinetic energy: E_k = ½mv² — depends on mass and speed squared.
• Gravitational potential energy: E_p = mgh — height measured from a chosen level.
• Work done: W = Fs — force in direction of movement; unit joule (J).
• Power: P = W/t; efficiency = useful output ÷ total input (× 100%).

What is Energy, Work and Power in Cambridge IGCSE Physics?

Energy is stored in different forms — kinetic, gravitational potential, chemical, elastic and more — and transfers between stores when work is done. Work done by a force equals force × distance moved in the direction of the force. Power is the rate of energy transfer. In exam questions you often equate lost gravitational potential with gained kinetic (ignoring friction) or calculate efficiency of a device.

You can read the full explanation, worked examples and notes on Tutopiya’s Energy, Work and Power subtopic page before you attempt questions.

The core ideas you must master

These four ideas appear again and again. Learn what each one means and the exam phrasing that signals it.

Idea	What it means	How the exam uses it
Kinetic energy	E_k = ½mv²	”Calculate the kinetic energy of the car”
GPE	E_p = mgh; g = 10 N/kg	”Find the potential energy gained”
Work done	W = Fs; 1 J = 1 N m	”Calculate the work done lifting the box”
Efficiency	useful ÷ total	”Calculate the efficiency of the motor”

How to solve energy transfer questions — step by step

The safest method works for roller-coaster, falling-object and machine-efficiency questions.

1. Identify the energy stores involved (e.g. GPE → KE).
2. Write the relevant formula — E_k, E_p, W or P.
3. Substitute in SI units (m, kg, s, N).
4. For conservation questions, equate energy before and after (if friction negligible).
5. State the answer in joules or watts with the correct unit.

Once you have worked through a few, test yourself with the free Energy, Work and Power quiz — it tells you fast whether the method has actually stuck.

Work vs energy vs power: which formula does the question want?

Students lose marks by using E_k when the question asks for work done, or forgetting to square velocity.

Situation	What to do	Typical signal words
Moving object	E_k = ½mv²	”speed”, “moving”, “kinetic energy”
Lifted or raised object	E_p = mgh	”height”, “lifted”, “above ground”
Force through distance	W = Fs	”push”, “pull”, “distance moved”
Rate of transfer	P = W/t	”per second”, “power of the motor”

Energy, Work and Power in past-paper wording: command words that matter

Most lost marks come from unit slips, not squaring v in E_k, or efficiency greater than 100%.

Command word / phrase	What the question wants	Typical stem
Calculate / Work out	Use the correct energy or power formula	”Work out the kinetic energy of the ball.”
Explain	Describe an energy transfer pathway	”Explain the energy changes as the ball falls.”
State	Name a store or unit	”State the unit of power.”
Show that	Prove a given energy value	”Show that the GPE lost is 500 J.”
Suggest	Improve efficiency	”Suggest how to reduce wasted energy.”

Worked exam-style stems (how to answer the wording)

Practising the wording — not just the formula — is what method marks reward. Here is how three real-style stems are answered.

1. “A 4 kg object moves at 3 m/s. Calculate its kinetic energy.” E_k = ½mv² = ½ × 4 × 3² = ½ × 4 × 9 = 18 J. Mark-scheme reward: ½mv² with v squared.
2. “A 2 kg mass is raised 5 m. Take g = 10 N/kg. Calculate the gain in GPE.” E_p = mgh = 2 × 10 × 5 = 100 J. Reward: all three factors shown.
3. “A machine transfers 200 J in 4 s. Calculate its power.” P = W/t = 200/4 = 50 W. Reward: division with unit W.

When you can recognise the wording instantly, work the full set on the Motion, Forces and Energy topical past-paper questions and the Energy, Work and Power quiz to lock the method in.

How Energy, Work and Power connects to the rest of Motion, Forces and Energy

Energy calculations use mass from Mass and Weight and speeds from Motion. Work done links to Forces, and momentum questions sometimes appear alongside kinetic energy in Momentum. When you are ready to move on, the Cambridge IGCSE Physics resource hub lets you jump straight from a weak subtopic into the next.

Common mistakes students make

• Forgetting to square v in E_k = ½mv².
• Using height in cm without converting to metres in E_p = mgh.
• Calculating work when force is not in the direction of motion.
• Expressing efficiency as a decimal when the question asks for a percentage.
• Assuming 100% efficiency without the question saying so.

When you need more support

If Energy, Work and Power questions keep tripping you up — especially choosing between formulas — work through the Motion, Forces and Energy topical past-paper questions and the Energy, Work and Power quiz to pinpoint the exact gap, then get focused help from a Cambridge IGCSE Physics tutor to fix it quickly.

Frequently asked questions

Is Energy, Work and Power hard in Cambridge IGCSE Physics? The formulas are few and predictable. Marks are lost on wrong formula choice, unit errors and not squaring speed.

What is the unit of energy and work? The joule (J). Power is measured in watts (W).

Can kinetic energy be negative? No — energy scalars are always positive. Direction is handled through velocity in other topics.

How do I revise Energy, Work and Power effectively? Read the subtopic notes, practise each formula separately, then take the Energy, Work and Power quiz. Mix in efficiency questions before moving on.

Ready to master Cambridge IGCSE Physics Energy, Work and Power?

Start with the Energy, Work and Power subtopic page, then book a free trial with a Cambridge IGCSE Physics specialist to turn Energy, Work and Power into guaranteed marks.

Ready to Excel in Your Studies?

Get personalised help from Tutopiya's expert tutors. Whether it's IGCSE, IB, A-Levels, or any other curriculum — we match you with the perfect tutor and your first session is free.

Book Your Free Trial