Impact Force

Key Stage 4 Higher

Meaning

An impact force is the force involved in the collision between two objects.

About Impact Forces

Impact forces are proportional to the change in momentum during a collision and inversely proportional to the time taken for the collision.

Impact forces explain the reason crashing at high speed is so dangerous and why cars have crumple zones and air bags. They both increase the time taken for the passengers to change momentum which reduces the force experienced by them.

Equation

NB: You do not need to remember the equation but you do need to be able to use it. Combining the two equations\[a=\frac{F}{m}\]

and

<math>a = \frac{\delta v}{t}<\math>

Gives

<math>\frac{F}{m} = \frac{\delta v}{t}<\math>

<math>F = \frac{m \delta v}{t}<\math>

Where\[F <\math> = The impact [[force]]. <math>m \delta v\] = The change in momentum.

<math>t<\math> = The time taken for the momentum to change.