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

Kinetic Friction and Newtons 2nd Law

  • Thread starter larryboi7
  • Start date
  • #1
8
0

Homework Statement


A car weighing 15000N experiences a drag force of 1200N. The car travels 30m/s on a level highway. The coefficient of kinetic friction is 0.2. If the car travels for 10s at this speed, calculate the power the engine produces.

The car then goes up a 10 degree constant incline. Calculate the additional force the engine must now provide. Find the power for friction on the incline.


Homework Equations


F = ma
MkFn
a= v/t


The Attempt at a Solution


so far i got that 15000= mg m = 1529.1
a = 3m/s^2
 

Answers and Replies

  • #2
PhanthomJay
Science Advisor
Homework Helper
Gold Member
7,136
476
I find the wording of this problem bothersome, since there is no kinetic friction involved unless the non-driving wheels are locked and skidding (the driving wheels are what propels the car forward, due to static friction, which does no work). Beyond that , the car is NOT accelerating...it is moving at constant speed. The driving force on the level surface is just the force necessary to overcome drag...and whatever kinetic friction force may be acting, if the non-driving wheels are locked.
 

Related Threads for: Kinetic Friction and Newtons 2nd Law

  • Last Post
Replies
4
Views
5K
Replies
18
Views
2K
Replies
5
Views
6K
  • Last Post
Replies
16
Views
1K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
5
Views
4K
  • Last Post
Replies
2
Views
1K
  • Last Post
Replies
3
Views
2K
Top