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Homework Help: Kinetic and Static Friction Problems

  1. Nov 5, 2012 #1
    Kinetic and Static Friction Problems Please Help!

    Mr. Bob slid a 250g plate 1.35m across the dish return counter. It slowed with a constant acceleration for 0.85s before coming to a stop.


    a) Find the magnitude of the force of friction

    b) What is the coefficient of kinetic friction between the plate and the counter?

    (I have no idea how to do a. but if I have a. I'll know b.)
     
  2. jcsd
  3. Nov 5, 2012 #2

    Nugatory

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    Staff: Mentor

    Re: Kinetic and Static Friction Problems Please Help!

    What is the relationship between force, mass, and acceleration? You know the mass and the acceleration, so you can calculate the force using that relationship.
     
  4. Nov 5, 2012 #3
    Re: Kinetic and Static Friction Problems Please Help!

    I know that is the direction I have to go but the answer has been alluding me. Could you please show me how to get the magnitude of friction!
     
  5. Nov 5, 2012 #4
    Re: Kinetic and Static Friction Problems Please Help!

    Have you drawn a free-body diagram for the plate?
    Look at the forces in the x-direction (only friction), and use Newtons's second law.
    Have you calculated the (constant) acceleration of the plate?
     
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