Solving Force Problem: 2kg Ball Falling From 10m

AI Thread Summary
A 2kg ball is dropped from a height of 10m, reaching a speed of 12.5m/s before impact. To calculate the work done against air friction, one must first determine the gravitational work using the formula Work = mg * distance, which yields 20J. The actual kinetic energy at the bottom can be calculated using the formula for kinetic energy. By comparing the expected speed without air resistance to the actual speed, the work done against air friction can be deduced. Understanding the distinction between force and work is crucial in solving this problem effectively.
sheevz
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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?
 
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Work is not force. Exerting a force is not the same as doing work.

Work = force*distance.
 
Last edited:
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 =]
 
What is the work done against gravity my friend?
 
so if work is mg*distance
then would the work be 2.0kg*10m= 20kgm?
 
or 20J, now what is the actual kinetic energy of the ball at the bottom?
 
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