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Homework Help: Momentum on a slope question

  1. Jan 27, 2008 #1
    1. The problem statement, all variables and given/known data
    A block of mass m = 2.80 kg slides down a 30.0° incline which is 3.60 m high. At the bottom, it strikes a block of mass M = 7.00 kg which is at rest on a horizontal surface, Fig. 7-41. (Assume a smooth transition at the bottom of the incline, an elastic collision, and ignore friction.)
    http://img141.imageshack.us/img141/4472/741ue2.gif [Broken]

    (a) Determine the speeds of the two blocks after the collision.
    Lighter Block:
    Heavier Block:

    (b) Determine how far back up the incline the smaller mass will go.

    2. Relevant equations

    v=final velocity
    u= Initial velocity
    s= Displacement


    3. The attempt at a solution

    I resolved to find acceleration perpendicular to the plain of motion and also the displacement, but as i was not given an initial velocity i cannot find out the final velocity of the small block as it hits the large block

    Does any one have any ideas as to how i would go about solving this question?
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Jan 27, 2008 #2
    i think you have to assume that the block starts at rest here.

    to start, use energy conservation methods to find the velocity of the small block at the bottom of the incline.
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