2.1.7—Equations that represent uniformly accelerated motion in a straight line

For constant acceleration, v=u+at, s=ut+½at², v²=u²+2as and s=½(u+v)t connect displacement, velocity, time and acceleration.

Define positive direction, use signed variables and choose the equation containing the known quantities. Split a journey when acceleration changes.

A car changing from 5 to 17 m s⁻¹ in 4 s has a=3 m s⁻² and displacement 44 m under the constant-a model.

SUVAT is not a universal motion formula set; variable acceleration needs calculus or graph methods.