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Homework Help: Momemtum/Energy Problems?

  1. Dec 1, 2005 #1
    Momemtum/Energy Problems??

    I'm having trouble with 2 problems here, I will give all the info that I am given but I still can't seem to solve the problems.
    1.) A block(m1) is released from the top a curved sloped plane and elastically collides with another block(m2).
    a.)How high does m1 go up the sloped plane after the collision?
    b.)What is the velocity of m2 after the collision?
    *Keep in mind that the system is frictionless

    2.)Two blocks(M and 3M) are compressing a massless spring and are connected by a rope. The rope is then burned and the blocks release in opposite directions, block 3M goes at a velocity of 2m/s
    a.) What is the velocity of block M?
    *this system is frictionless as well.
  2. jcsd
  3. Dec 1, 2005 #2
    #2 is basic conservation of momentum.

    for the first one i'd need to know the course level to be able to give you any useful advice.
  4. Dec 1, 2005 #3
    its mechanical physics, first level, at penn state its called physics 211, dont know if that helps any. How do you do the first one through basic conservation of momentum, I couldn't figure it out.
  5. Dec 1, 2005 #4

    Physics Monkey

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    Homework Helper

    These problems are all about using conservation of momentum and energy in the right places. For the first problem, you can figure out the initial speed of m1 in terms of the height it was released at, right? Now you have to describe the collision. Since m2 is at rest and you know m1's initial velocity, do you have enough information to find out the final velocities of the two masses (remember the collision is elastic)? A knowledge of these two final velocities is sufficient to answer the two questions.

    Problem two, as has already been pointed out, is a simple application of momentum conservation for the system.
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