5.2.3—The equations of motion, the formula for kinetic energy EK = 1/2 mv2
- Syllabus
- 9702–2028–2029
- Objective
- 5.2.3
- Level
- AS
Use constant-acceleration equations to connect motion with kinetic-energy changes
The constant-acceleration equations give links between u, v, a, s and t; kinetic energy is E_K=½mv² and changes when the net work changes speed.
Check that acceleration is constant before selecting an SUVAT equation, then use the signed velocity and the correct mass in the energy calculation.
An object accelerating from rest at 2.0 m s⁻² for 3.0 s reaches 6.0 m s⁻¹, so its kinetic energy is 18m joules for mass m.
SUVAT is not valid for arbitrary changing acceleration, and kinetic energy depends on speed squared, not velocity sign.
ConceptA-Level CAIE Physics AS