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Length of Skid Marks

  • Thread starter wcbryant87
  • Start date
  • #1
14
0

Homework Statement



A 1000 kg car traveling at a speed of 40 m/s skids to a halt on wet concrete where [tex]\mu[/tex]k = 0.60. How long are the skid marks?



Homework Equations



Vf = Vi + 2ad
fk = [tex]\mu[/tex]kN = ma



The Attempt at a Solution


This problem is driving me crazy. Nowhere in the book does it tell you how to do this or even a similar problem. Plus, online, all I can find is how to find the speed once you've found the length of the skid marks! And yes, I tried doing the problem in reverse but the answer never comes out right.

Here is what I've done.

1000 * 9.8 = 9800
9800 *.6 = 5880
acceleration = 5880/1000 = 5.88

0 = 40 + 2 * 5.88 * d
d = 3.4

I know I've done something incredibly wrong here because the answer in the back of the book is 136!

I appreciate the help

a(1000) = 5800

Homework Statement





Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #2
hage567
Homework Helper
1,509
2
0 = 40 + 2 * 5.88 * d
That 40 should be squared!
 
  • #3
14
0
oh wow. thank you so much!
 

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