This key facts covers Key Facts — Kinetic Energy within Kinetic Energy for GCSE Physics. Revise Kinetic Energy in Energy for GCSE Physics with 15 exam-style questions and 30 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 3 of 15 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
📚 Key Facts — Kinetic Energy
What it is: The energy stored in any object due to its motion. If it's moving, it has kinetic energy.
Key relationships:
- KE ∝ mass (m) — doubling mass doubles KE (directly proportional)
- KE ∝ velocity² (v²) — doubling velocity QUADRUPLES KE
- The ½ factor comes from the calculus of integrating F = ma
Units:
- Kinetic Energy — Joules (J)
- Mass — Kilograms (kg) — NOT grams!
- Velocity — Metres per second (m/s) — NOT km/h or mph!
💡 CRITICAL: The ½ in the equation is essential. Forgetting it will double your answer! Also, square the velocity FIRST before multiplying by mass.
Practice questions for Kinetic Energy
Which of the following objects has kinetic energy stored in its kinetic energy store?
A car travels at 20 m/s. The driver then doubles their speed to 40 m/s. Explain what happens to the kinetic energy of the car and by what factor it changes.