This higher tier covers Higher Tier Only: KE from the Equations of Motion 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 12 of 15 in this topic. This section is most useful once the core foundation idea is secure, because it adds the detail that pushes answers higher.
🎓 Higher Tier Only: KE from the Equations of Motion
The ½ in E_k = ½mv² can be derived from the equations of motion. Starting from v² = u² + 2as (where u = 0 for an object starting from rest):
- v² = 2as, so s = v²/(2a)
- Work done = F × s = ma × v²/(2a) = ½mv²
This shows that KE is literally just the work done to accelerate an object from rest to speed v. No magic — just F = ma and W = Fs combined.
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.