# How do I Find Average Force in a Force vs Time graph?

1. Feb 22, 2009

### haroldham

This is really simple, but I can not remember how to find the average force in a Force vs TIme graph.

2. Feb 22, 2009

### robphy

Think about the height of a "[certain] rectangle." Think area.

3. Feb 22, 2009

### haroldham

Ok, you completely lost me, but I think I figured it out. This certain graph increases, remains constant, then decreases. Do I take the final force of each section, add it to the initial force of each section, divide that value by the time of that section, then average those together?

4. Feb 22, 2009

### robphy

Presumably, you mean "time-averaged force".
The area under your graph is equal to the impulse (ie, the change in momentum).
The "time-averaged force" you seek is the constant force you would apply in the same amount of time in order to obtain the same change in momentum. Translate the last sentence into facts about the graph.

5. Feb 22, 2009

### haroldham

Oh, ok I get it. It is impulse divided by time.