Solving Force Problem: 2kg Ball Falling From 10m

[sheevz]

Force Problem!

Homework Statement

a ball of mass 2.0kg is dropped from a height of 10m. the speed of the ball is measured as 12.5m/s just before it hits the ground. what was the work done against air friction during this fall?

Homework Equations

The Attempt at a Solution

totally lost on where to begin can someone help me start? I am not finding anything on work itself as a force, is it a force?

 

[konthelion]

Work is not force. Exerting a force is not the same as doing work.

Work = force*distance.

 

[Gib Z]

So in this case, Work = mg * 10m. See what that comes out to first.

Then, using some basic equations of motion, you want to work out what the speed of the ball would have been, neglecting air resistance. Now, we know what the actual speed was, accounted for air resistance. Then use the formula for kinetic energy to get you to the end =]

 

[physixguru]

What is the work done against gravity my friend?

 

[sheevz]

so if work is mg*distance
then would the work be 2.0kg*10m= 20kgm?

 

[arunbg]

or 20J, now what is the actual kinetic energy of the ball at the bottom?