Physics 101 Q

1. Mar 27, 2009

Okki2

1. The problem statement, all variables and given/known data

200kg object 10m in the sky falls 8 meters and hits a pole. pole goes 8cm into ground.

2. Relevant equations
Average Force for the poles descent into the ground (8cm). Answer in Newtons.

3. The attempt at a solution

E(p) = mgh = 200*9.82*8J = 15712J = 15.7KJ

hmmm....

2. Mar 27, 2009

Hannisch

How much do you know about the concept of work?

3. Mar 27, 2009

Okki2

W=F*S

F = mg = 200*9.82 = 1964N

W = 1964N*8M = 15712N ?

hmm..im not getting the right answer.

4. Mar 29, 2009

Hannisch

Yes, work = force * distance. There's also a relationship that says that work = difference in kinetic energy. If you can find the amount of potential energy that's been made into kinetic energy during the fall, you can find the amount of kinetic energy lost when the object pushes the pole down, which is then equal to the work done.

The force in W = F*d is the one you want to find. And the unit of work is not, as you say in your previous post, Newton. It's Joules :)

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