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Homework Help: Determine the amount of kinetic energy lost due to the collision

  1. May 5, 2010 #1
    1. The problem statement, all variables and given/known data
    So I am faced with a theoretical equation which uses all variables in terms of Mass,Length,Coefficient of friction which i will just write as u, radius R and gravity g. Block A of mass M is released from rest at the top of an arc ramp which is frictionless it contacts block B of mass M at the bottom inelastically. the Two blocks move together to the sliding past a distance L along a flat track of friction u. Express answers in terms of M,L,u,R and g

    a determine the speed of block A before it hits block B

    b determine the speed of the combined blocks immediately after collision

    c determine the amount of Kinetic energy lost due to the collision.

    d the specific heat of the the blocks is c. determine the temperature rise that results from the collision in terms of c and other give quatities if no energy is transferred to the track or air.

    e determine additional thermal energy that is generated as the blocks move from y to p

    2. Relevant equations

    3. The attempt at a solution

    a mgh=1/2mv^2 v=(2gh)^(1/2)

    b determine the speed of the combined blocks after collision. m(2gh)^(1/2)=2m(2gh)^(1/2)/2

    c this is where i get lost, i understand Ke is lost to an inelastic collision, but i don't understand how to determine how much?
  2. jcsd
  3. May 5, 2010 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Seems reasonable. What's h in terms of R?

    Not sure what you're doing here. Call the speed after the collision "V". Set up your equation and solve for V.

    What's the total KE of the blocks before the collision? After the collision? Subtract!
  4. May 5, 2010 #3
    I realized that R could be substituted in for h, and I seem to have ended up with the right answer for c. as to part b i was conserving momentum and with twice the mass the velocity had to be halved. Thank you for your help!
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