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Homework Help: Sled question

  1. Feb 1, 2007 #1
    Sled question

    I have a physics midterm tonite and i was trying some of the practice tests and i got stuck on this question, ur help would be greatly appreciated :)

    1. The problem:
    A sled is travelling at 4.00m/s along a horizontal stretch of snow. The coefficeint of kinetic friction is Uk=0.05 and the coefficient of static friction Us=0.07. How far does the sled go before stopping?

    2.This is my thought process:
    Ok im assuming its moving at constant speed and the acceleration is negative so i drew the FBD with weight down, normal forced up and force of kinetic friction to the left. (Assuming its moving to the right) i thought that Fnet= force of friction (x-direction) = m a , and that by solving for acceleration i can use it to find out the distance however i dont have mass so I didnt know wat to do?! Any suggestions?

    3. The answer is actually 16.3m
  2. jcsd
  3. Feb 1, 2007 #2
    Why would you need to know the mass?
  4. Feb 1, 2007 #3
    I think if you just follow thru with what you have done already, you are there:

    set ma=frictional force and solve for a.
  5. Feb 1, 2007 #4
    well if what i said was correct and fnet(x-direction) = ma = Ff, then
    ma = Ukmg right? ohhh ic....lol so a=Ukg.... my bad this is where i make another stupid mistake....THANKS
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