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Hockey Puck Friction Problem

  • Thread starter bbreezy
  • Start date
  • #1
7
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I am having trouble with this problem, it states:
A hockey puck on a frozen pond with an initial speed of 14.1 m/s stops after sliding a distance of 198.9 m. Calculate the average value of the coefficient of kinetic friction between the puck and the ice.

I tried using the equation uk=a/g but didnt work out for me. Any help?
 

Answers and Replies

  • #2
cepheid
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Welcome to PF bbreezy!

Using basic kinematics, you can figure out what the object's acceleration must have been for it to require that stopping distance in order to come to rest from that initial speed.

Once you know the acceleration of the object, you know the net force on the object (due to Newton's second law). In this case, the net force is the frictional force, since it is the only one that acts on the object. So, equating the net force to the frictional force, you will indeed find that the expression you posted for the coefficient of friction is correct (since it will just turn out to be the ratio of the net force to the weight, and the m's will cancel).

So, if you didn't get the right answer, you must not have computed 'a' correctly. Can you post your calculations here?
 
  • #3
7
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Vi+2ad = 0
14.1+2(a)(198) = 0
2(a)(198) = -14.1

then this is where I think I am messing up
 
  • #4
cepheid
Staff Emeritus
Science Advisor
Gold Member
5,192
35
Vi+2ad = 0
14.1+2(a)(198) = 0
2(a)(198) = -14.1

then this is where I think I am messing up
It should really be:

vi2 + 2ad = 0
 
Last edited:

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