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Some guidance please! Newton's Laws

  1. Nov 3, 2004 #1
    A1000N crate is being pushed across a level floor at a constant speed by a force of 300N at an angle of 20 degrees below the horizontal.
    (a) what is the coefficient of kinetic friction between the crate and the floor

    I was able to find this which is = .26

    (b) If the 300N force is instead pulling the block at an angle of 20 degrees above the horizontal what will the acceleration of the crate be?(assume that the coefficient of friction is the same as found in (a))

    Help I need guidance on this part!
     
  2. jcsd
  3. Nov 3, 2004 #2
    Have you tried working this out yourself? Draw a freebody diagram and write the equation of motion in the horizontal direction, solve for a.
     
  4. Nov 3, 2004 #3
    I was afraid it would seem that way if i didn't describe all my attempts to solve it.

    I am confused, my best bet was to use the equation
    F= m*a
    because i know that I could find my acceleration from this formula
    So I applied it using the numbers from the problem
    m=w/9.8
    m=897/9.8 = 91.53
    F=282

    282/91.53 = a = 3.1

    which is not right
    plus i didn't use the coefficient

    So i thought, if i apply
    F=μN
    F=.26 * 897 = 233

    then
    233/91.53= 2.54
    also not right

    so i'm lost.
     
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