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

Ap physics friction force please help

  • #1
163
0
Ap physics friction force please help!!!!

Homework Statement



A 1000kg car traveling at a speed of 40m/s skids to a halt on wet concrete where the friction force is 6000N. How far does the car slide before coming to a stop?

Homework Equations




F=mv^2 / r
1000 kg x (40 m/s^2) / r = 6000 N
I got 266.7


The Attempt at a Solution


I came up with a positive number and it should be a negative number... What am I doing wrong?!
 

Answers and Replies

  • #2
Simon Bridge
Science Advisor
Homework Helper
17,847
1,644
Why would you expect a negative number?
(And don't forget units.)

F=mv^2/r is for centripetal force isn't it? Is the car going in a circle?
 
  • #3
380
7

Homework Statement


I came up with a positive number and it should be a negative number... What am I doing wrong?!
Well..it always depends on which direction you choose to be positive and which negative.
However, the equation you used wasn't correct. Think it in terms of work and energy.
 

Related Threads on Ap physics friction force please help

  • Last Post
Replies
9
Views
3K
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
4
Views
796
  • Last Post
Replies
4
Views
1K
  • Last Post
Replies
10
Views
966
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
2
Views
1K
  • Last Post
Replies
1
Views
3K
Top