February 2nd, 2008

Using conservation of energy determine the speed of the 3kg mass as the 5kg mass hits the ground?

rachhar123 asked:


Two masses (5kg, 3kg) on Atwood’s Machine.Vo=0.
At t=0, 5kg is 4m above ground, 3kg is on ground. What is final speed of the 3kg mass as the 5kg mass hits the ground? Use conservation fo energy to determine.

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This entry was posted on Saturday, February 2nd, 2008 at 3:57 am and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

One Response to “Using conservation of energy determine the speed of the 3kg mass as the 5kg mass hits the ground?”

  1. David Zukertort Rudel Says:
    February 5th, 2008 at 12:10 am

    At the start:

    5kg mass has 0 kinetic energy and 5*4*9.8 = 196 joules of potential energy.

    3kg mass has 0 kinetic energy and 0 potential energy.

    Total energy = 196 J.

    At end:

    5kg mass and 3kg mass are both moving with some velocity v.

    5kg mass has 1/2*5*v^2 kinetic energy and 0 potential energy

    3kg mass has 1/2*3*v^2 kinetic energy and 3*9.8*4 = 117.6 Joules of potential energy.

    Total energy = 4v^2 + 117.6 J.

    Set this equal to the energy before and solve for v.