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Homework Help: Distance question!

  1. Mar 4, 2010 #1
    1. The problem statement, all variables and given/known data
    A 11 kg block slides down a frictionless slope
    which is at angle θ = 24◦. Starting from rest,
    the time to slide down is t = 1.85 s.
    The acceleration of gravity is 9.8 m/s2 .
    (look at image)
    What total distance s did the block slide?
    Answer in units of m.

    2. Relevant equations
    F=ma
    F=mg
    tan(theta) = Fy/Fx

    3. The attempt at a solution
    I calculated the acceleration, a = F/m = 22.01116038m/s^2.
    I used the time 1.85sec and the acceleration to find the velocity, v = 40.72064671m/s.
    I don't know how to proceed from this point?
     

    Attached Files:

  2. jcsd
  3. Mar 4, 2010 #2
    What numbers did you use for F/m?

    22 is way too high. It has to be under 9.8
     
  4. Mar 5, 2010 #3
    I found Fn = mg = 107.8
    I used Force = Fn/tan24 = 242.1227642N
    then i found a = F/m = 242.1227642N/ 11kg = 22.01116038 m/s^2
     
  5. Mar 5, 2010 #4

    Char. Limit

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    Gold Member

    I think you should have multiplied by tan(theta), not divided by it.
     
  6. Mar 5, 2010 #5
    thanks
     
  7. Mar 6, 2010 #6
    There's your mistake.

    Multiply the force by sin(theta) then use that force in F/m to get your acceleration.
     
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