# I Impact force

1. May 30, 2016

### Dynamics101

If force isn't constant in a system, how can I calculate impact force of two bodies accelerating towards each other.
Can I use the Work formula since energy in a system is conserved?
Give an example, of a way I can calculate impact force in a system in which force is not constant.
Thanks.

2. May 30, 2016

### Simon Bridge

You don't. The concept of "impact force" makes no sense.
What you do is you plot a Force-time graph: the area under that graph is the change in momentum.

It is very unusual for the energy in an impact to be conserved in a way that makes the calculation easy: hoe do you account for the energy that goes to sound, heat, or deformation of the impacting objects?