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Homework Help: Friction Acceleration

  1. Oct 13, 2008 #1
    1. The problem statement, all variables and given/known data

    A 219-kg crate is pushed horizontally with a force of 710 N. If the coefficient of friction is 0.20, calculate the acceleration of the crate.

    force of friction= 219kg *.2 =43.8N?
    2. Relevant equations

    3. The attempt at a solution
    I am not sure at all how to calculate the acceleration and what to use as the "F" to calcuate it
  2. jcsd
  3. Oct 13, 2008 #2
    friction is normal force*coefficient of friction

    thus the force of friction would by 219*gravity*.2

    The equation, F=ma, is right.

    But friction always points in the opposite direction so it would set up like this:

    Force(710) - friction = ma

    then solve for a!

    Hope this helps.
  4. Oct 13, 2008 #3
    yeah that does help
    since I didnt realize you had to subtract the 710 with the Ff

    so 710-429.24=280.76N
  5. Oct 13, 2008 #4
    yup, I didn't do the actually calculations, but it looks right.
    An easy way to remember this is :

    winner force - loser force = ma

    And free-body diagramming it helps too
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