This topic summary covers Knowledge Organiser: Gravitational Potential Energy within Gravitational Potential Energy for GCSE Physics. Revise Gravitational Potential Energy in Energy for GCSE Physics with 15 exam-style questions and 6 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 16 of 16 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Knowledge Organiser: Gravitational Potential Energy
Key Terms
- GPE: energy stored due to position in a gravitational field
- g: gravitational field strength (10 N/kg on Earth)
- h: vertical height above reference point (m)
- Reference point: level from which height is measured
Key Equation
- E_p = mgh
- Rearranged: h = E_p / (mg)
- Rearranged: m = E_p / (gh)
- Conservation: GPE lost = KE gained
Key Facts
- GPE ∝ mass and ∝ height (both direct)
- g = 10 N/kg on Earth
- Height must be VERTICAL, not slope distance
- In free fall (no friction): all GPE → KE
Exam Tips
- Use vertical height only — not slope length
- mgh = ½mv² for falling objects — mass cancels!
- Always square root at the end when finding v
- Check g value given — may differ from 10 N/kg
Common Mistakes
- Using slope instead of vertical height: h in Eₚ = mgh must be the vertical height — not the length of a ramp or slope
- Wrong units for g: g = 10 N/kg (or 9.8 N/kg) — check which value the exam provides; using 9.8 when the question says 10 loses marks
- Forgetting to convert mass: Mass must be in kg, height in metres — always convert grams and centimetres first
- Misapplying KE = GPE: When mass cancels, students sometimes forget to square root when finding v — always show full working
- Confusing GPE with work done: GPE gained equals work done against gravity — they are equal only when no energy is wasted
Practice questions for Gravitational Potential Energy
What is the value of gravitational field strength (g) on Earth?
Explain how gravitational potential energy is related to an object's mass and height. Refer to the equation Ep = mgh in your answer.
Quick recall flashcards
GPE ∝ mass
double the mass, double the GPE (directly proportional)
GPE ∝ g
same object at same height on Moon has 1/6 the GPE as on Earth