• Support PF! Buy your school textbooks, materials and every day products Here!

Force Problem

  • Thread starter sheevz
  • Start date
  • #1
7
0
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? im not finding anything on work itself as a force, is it a force?
 

Answers and Replies

  • #2
238
0
Work is not force. Exerting a force is not the same as doing work.

Work = force*distance.
 
Last edited:
  • #3
Gib Z
Homework Helper
3,346
4
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 =]
 
  • #4
335
0
What is the work done against gravity my friend?
 
  • #5
7
0
so if work is mg*distance
then would the work be 2.0kg*10m= 20kgm?
 
  • #6
590
0
or 20J, now what is the actual kinetic energy of the ball at the bottom?
 

Related Threads for: Force Problem

  • Last Post
Replies
3
Views
544
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
9
Views
609
  • Last Post
Replies
1
Views
939
  • Last Post
Replies
6
Views
465
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
2
Views
956
  • Last Post
Replies
5
Views
1K
Top