Coefficient of kinetic Friction given velocity and distance.

  • Thread starter pech0706
  • Start date
  • #1
pech0706
14
0

Homework Statement


A car is moving with a velocity of 20m/s when the brakes are applied and the wheels lock (stop spinning), The car then slides to a stop in 40m. FInd the coefficient of kinitic friction between the tires and the road.



Homework Equations


F=ma
Ffriction=coefficient fo friction*N
N=mg

The Attempt at a Solution


I have drawn a picture and free body diagram, but that's as far as I've gotten. I'm stuck because I don't know how to calculate the normal force with out the mass, and I don't now how to find the coefficient without N. I know the answer is 0.51, but I do not know how to get there.
 

Answers and Replies

  • #2
cupid.callin
1,137
0
dont worry about mass.
take it as m
it will get cancelled in the process.
 
  • #3
pech0706
14
0
So, basically that means the total force acting on the car is the velocity and the frictional force. After ignoring the mass though, I'm still stuck. I don't know how to find the frictional force or the coefficent of friciton when ignoring mass.
 
  • #4
cupid.callin
1,137
0
Dont ignore mass, take it as m.

Then do the general method and find the answer.
mass wont be any problem
 

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