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A couple of problems on motion and force

  1. Dec 4, 2006 #1
    1. The problem statement, all variables and given/known data

    A flatbed truck is carrying a 3200-kg crate of heavy machinery. If the coefficient of static friction between the create and the bed of the truck is 0.65, what is the maximum rate at which the driver can decelerate when coming to a stop in order to avoid crushing the cab with the crate?

    2. Relevant equations

    fric = u*N
    Fnet = m * a

    3. The attempt at a solution

    N = 3200*9.8 = 31360
    fric = 0.65 * 31360 = 20384 N

    thats as far as I got
    Last edited: Dec 4, 2006
  2. jcsd
  3. Dec 4, 2006 #2
    What are d and e? The frictional force is equal to the coefficient of friction, mu, times the normal force which is usually denoted by N.
  4. Dec 4, 2006 #3


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    Homework Helper

    For 1), use Newton's 2nd law, F = ma. F is the decelerating force and the same force F acts on both the truck and the crate. But the actual force that slows down the crate is the force of friction between the crate and the floor of the truck. So what is the maximum frictional force you can have ?

    2) is similar. Use F = ma and Fr = μm to get a. And minimum stopping distance comes from maximum decelerating (frictional) force.
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