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Applying Newton's Laws Projected Up an Incline

  1. Oct 21, 2009 #1
    Projected Up an Incline A block is projected up a frictionless inclined plane with initial speed v1 = 3.43 m/s. The angle of incline is θ = 32.5°.
    (a) How far up the plane does it go?

    (b) How long does it take to get there?

    (c) What is its speed when it gets back to the bottom?



    What i got soo far
    v * T = d

    a) 3.43 * .674 = 2.31 m


    b)vi = 3.43
    vf = 0
    a = - 9.80 sin32.5
    t = ?

    t = (vf - vi) / a
    t = 3.43 / (9.80 sin32.5)
    t = 0.674




    c) dont even know where to begin on this one
     
  2. jcsd
  3. Oct 21, 2009 #2
    You can solve the problem using the equations of motion

    vf2 = vi2 +2ad ---------(1)
    vf = vi + at --------(2)
    where vf and vi are the final and initial velocity respectively and a is the acceleration, t is the time

    Using equation (1), you can solve for d
    and using (2) you can solve for t

    For the third question, you have to consider the distance the block has traveled
    and the block would have this length of 'track' to go back to the bottom.

    So, again you can use (1) to solve for vf
    (which must equal to 3.43m/s, to the opposite direction)

    i don't get what is 'T' used for question a
    your working for b is correct but i get 0.651s as my answer, using the same working
     
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