Gravitational potential energy and kinetic energy
Cambridge A-Level Physics (9702) · Unit 5: Work, energy and power · 7 flashcards
Gravitational potential energy and kinetic energy is topic 5.2 in the Cambridge A-Level Physics (9702) syllabus , positioned in Unit 5 — Work, energy and power , alongside Energy conservation. In one line: ΔEp = mgΔh, where 'm' is mass, 'g' is the acceleration due to gravity, and 'Δh' is the change in height. This formula applies near the Earth's surface where 'g' is approximately constant.
Marked as AS Level: examined at AS Level in Paper 1 (Multiple Choice), Paper 2 (AS Structured Questions) and Paper 3 (Advanced Practical Skills). The same content may also be assumed in Paper 4 (A Level Structured Questions).
The deck below contains 7 flashcards — 2 definitions, 1 key concept, 2 calculations and 2 derivations — covering the precise wording mark schemes reward. Use the 2 definition cards to lock down command-word answers (define, state), then move on to the concept and calculation cards to handle explain, describe, calculate and compare questions.
Formula for the change in gravitational potential energy (ΔEp) in a uniform gravitational field
ΔEp = mgΔh, where 'm' is mass, 'g' is the acceleration due to gravity, and 'Δh' is the change in height. This formula applies near the Earth's surface where 'g' is approximately constant.
What the Cambridge 9702 syllabus says
2025-2027 syllabus, in our words · AS LevelWhat the syllabus expects you to be able to do in this topic, in plain English. For the exact wording, see the official syllabus (PDF).
- Derive ΔEp = mgΔh for changes in gravitational potential energy in a uniform gravitational field, starting from W = Fs.
- Recall ΔEp = mgΔh and use it for changes in gravitational potential energy in a uniform gravitational field.
- Derive the kinetic energy formula Ek = ½mv² from the equations of motion.
- Recall Ek = ½mv² and use it.
Cambridge syllabus keywords to use in your answers
These are the official Cambridge 9702 terms tagged to this section. Mark schemes credit responses that use the exact term — weave them into your answers verbatim rather than paraphrasing.
Tips to avoid common mistakes in Gravitational potential energy and kinetic energy
- › Always use the vertical height (h) in the ΔEp = mgh equation, regardless of the path taken by the object.
Derive the formula for the change in gravitational potential energy (ΔEp) in a uniform gravitational field using W = Fs.
Work done (W) equals force (F) times distance (s). In this case, the force is weight (mg) and the distance is the change in height (Δh). Therefore, ΔEp = W = Fs = mgΔh.
State the formula for the change in gravitational potential energy (ΔEp) in a uniform gravitational field.
ΔEp = mgΔh, where 'm' is mass, 'g' is the acceleration due to gravity, and 'Δh' is the change in height. This formula applies near the Earth's surface where 'g' is approximately constant.
A 2 kg mass is lifted 1.5 m vertically. Calculate the change in its gravitational potential energy.
Using ΔEp = mgΔh, where m = 2 kg, g = 9.81 m/s², and Δh = 1.5 m, we get ΔEp = (2 kg)(9.81 m/s²)(1.5 m) = 29.43 J.
Derive the formula for kinetic energy (Ek) using equations of motion.
Starting with v² = u² + 2as, rearrange to get s = (v² - u²)/2a. Work done, W = Fs = mas = ma(v² - u²)/2a = (1/2)mv² - (1/2)mu². If starting from rest (u=0), then Ek = (1/2)mv².
State the formula for kinetic energy (Ek).
Ek = (1/2)mv², where 'm' is the mass of the object and 'v' is its velocity. Kinetic energy is the energy an object possesses due to its motion.
Calculate the kinetic energy of a 5 kg object moving at 4 m/s.
Using Ek = (1/2)mv², where m = 5 kg and v = 4 m/s, we get Ek = (1/2)(5 kg)(4 m/s)² = 40 J.
Describe the relationship between kinetic energy and velocity.
Kinetic energy is directly proportional to the square of the velocity. This means that if the velocity doubles, the kinetic energy quadruples.
Review the material
Read full revision notes on Gravitational potential energy and kinetic energy — definitions, equations, common mistakes, and exam tips.
Read NotesMore topics in Unit 5 — Work, energy and power
Gravitational potential energy and kinetic energy sits alongside these A-Level Physics decks in the same syllabus unit. Each uses the same spaced-repetition system, so progress in one informs the next.
Key terms covered in this Gravitational potential energy and kinetic energy deck
Every term below is defined in the flashcards above. Use the list as a quick recall test before your exam — if you can't define one of these in your own words, flip back to that card.
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