Physics Laws & Theorems
Intermediate

Conservation of Momentum

Total momentum of an isolated system stays constant.

Formula

∑pi=∑pf\sum p_i = \sum p_f

Variables

p_iInitial momenta
p_fFinal momenta

Example

When two skaters push apart, their momenta are equal and opposite — total stays zero.

Did You Know?

Total momentum before and after any collision is identical — even in a chaotic multi-car pileup.

momentumconservationlaw