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Homework Help: Speed of an object on a ramp.

  1. Nov 4, 2007 #1
    1. The problem statement, all variables and given/known data
    A block starts from rest at a heigh of 8m on a fixed inclined plane. The acceleration of gravity is 9.8m/s^2. What is the speed of the block at the bottom of the ramp? Answer in units of m/s.

    Block mass = 4.5kg
    coefficient of friction = 0.19
    Angle of incline = 29 degrees
    Distance from block to end of ramp = 8m

    2. Relevant equations

    3. The attempt at a solution

    using a = (sin(theta)-ucos(theta)g I got 3.122 for a. However i'm not sure how to get a final velocity for the block from just the acceleration and distance.
  2. jcsd
  3. Nov 4, 2007 #2


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    Homework Helper

    There's a kinematics equation that will directly give you the final velocity v2.

    You know v1, a and d... you need v2... which equation will let you get it?
  4. Nov 4, 2007 #3
    that would be sqrt of 2ax since vi is 0, but that answer comes out to 7.068 which is wrong so i must have my acceleration wrong
  5. Nov 4, 2007 #4


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    Homework Helper

    your acceleration looks right to me.

    Did you use the right distance?

    They give the height as 8m. But what is the length of the incline?
  6. Nov 4, 2007 #5
    oh man i'm such an idiot. That would be the problem.
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