# Homework Help: Force of a shot

1. Sep 20, 2010

### TheNovice

1. What is the average force exerted by a shot-putter on a 7.0 kilogram shot if the shot is moved through a distance of 2.8 meters and is released with a speed of 13 m/s?

2. F=ma, x = vo t + 1/2 at^2, v=vo at

3. I think you get time by using D = vt, but when I use this time and plug it into the distance equation above I get a weird answer. The real answer should be in the ballpark of 200 Newtons.

2. Sep 20, 2010

### Heimisson

ok I'm not sure how much calculus you know but the chain rule allows you to write:
F=ma=m$$\frac{dv}{dx}$$$$\frac{dx}{dt}$$=m$$\frac{dv}{dx}$$v
this means the F =mv*(change in velocity)/(change in position)

However this gives me about 400 N so I might be forgetting something.

3. Sep 20, 2010

### TheNovice

Thanks for the response

But I'm in an introductory physics course; calculus is a bit too much for me.

I'll play around with the numbers some more.

The problem seems really easy... I just can't get the right answer.