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Kinematics

Kinematics describes the motion itself without looking at the forces that cause it: position, velocity and acceleration. With constant acceleration, for example free fall or uniform braking, three simple formulas connect speed, time and distance.

v = v_0 + at

velocity as a function of time

s = v_0t + \tfrac12at^2

distance as a function of time

v^2 = v_0^2 + 2as

velocity without time

Symbols

$v_0,\ v$	initial/final velocity	m/s
$a$	acceleration (constant)	m/s²
$s$	distance travelled	m

Example

A car from 0 to 20 m/s in 5 s, constant $a$ :

$a = (20-0)/5 = 4$ m/s².

The formulas above only hold when the acceleration is constant.

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Part of Statics and Dynamics: Dynamics.