Equations of motion · Grade 11
When the acceleration is constant, five quantities describe the motion: displacement s, initial velocity u, final velocity v, acceleration a and time t. The SUVAT equations link them, so if you know three you can find the others. Free fall is the classic case, with a = 9.8 m/s² downwards.
Key facts
- v = u + at
- s = ut + ½at²
- v² = u² + 2as
- s = ½(u + v)t
- Write down s, u, v, a and t. Cross out the one you don’t need. Pick the equation without it.
- Choose a positive direction. For things thrown upwards, a = −9.8 m/s².