Physics 101: Average Force Calculation for a Falling Object Hitting a Pole

[Okki2]

Homework Statement

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

Homework Equations

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

The Attempt at a Solution

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

hmmm...

 

[Hannisch]

How much do you know about the concept of work?

 

[Okki2]

W=F*S

F = mg = 200*9.82 = 1964N

W = 1964N*8M = 15712N ?

hmm..im not getting the right answer.

 

[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 :)