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Calculate velocity of block down a ramp using energy conserv

  1. Dec 12, 2015 #1
    1. The problem statement, all variables and given/known data

    A 2kg block slides down a 3 m long ramp that is inclined at 40 degrees. The coefficient of friction is .2

    What is the velocity when it hits the bottom of the ramp?

    2. Relevant equations

    Kinetic = 1/2 mv^2
    Potential = mgh
    Work of friction: Fnμ*(displacement)

    3. The attempt at a solution

    1/2mv^2 + mgh = 1/2mv^2 + mgh - Fnμ*(displacement)

    v = 8.237.

    I don't think that's right, because I didn't take into account the angle. What do I need to do?
     
  2. jcsd
  3. Dec 12, 2015 #2

    Simon Bridge

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    Draw a picture.
     
  4. Dec 14, 2015 #3
    You can start by drawing a free body diagram (those always help).
     
  5. Dec 14, 2015 #4

    Simon Bridge

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    Not in this case ... a fbd won't tell OP the correct height the block falls.
     
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