Forces & Motion - Equations & Definitions & Units

equation for average speed

average speed = distance moved/time taken

equation for acceleration

acceleration = change in velocity/time taken

a= (v-u)/t

equation for final speed

final speed²= initial speed² + (2 x acceleration x distance moved)

v² = u² + (2 x a x s)

vector quantity

a vector quantity has both direction and magnitude

scalar quantity

a scalar quantity has only magnitude

friction

a force that opposes motion

equation for weight

weight = mass x gravitational field strength

W = m x g

equation for force (mass)

force = mass x acceleration

F = m x a

equation for momentum

momentum = mass x velocity

p = m x v

equation for force (momentum)

force = change in momentum/time taken

F = (mv-mu)/t

Hooke’s law

The extension of a spring is directly proportional to the force applied, provided that the limit of proportionality is not exceeded.

Kilogram

kg

metre

m

metre/second

m/s

metre/second²

m/s²

newton

N

second

s

newton/kilogram

N/kg

newton metre

Nm

Kilogram metre/second

kg m/s