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Homework Help: Falling egg question (with energy equations)

  1. Nov 30, 2008 #1
    An egg of mass 5.8*10^-2 is dropped from a height of 1.5m onto a floor. Assuming air resistance is negligable, calculate for the egg:

    a) loss of potential energy.
    b) the kinetic enrgy just before impact.
    c) the speed just before impact
    d) the momentum just before impact.

    So far i have done the potential energy one, and now im stuck on the others. As the equation for KE is KE=1/2mV^2 but we do not know the velocity. And i cannot find out the velocity because we dont have the time either. So i was just wondering how i would work out b-d as all of their equations require velocity.


  2. jcsd
  3. Nov 30, 2008 #2
    I hope you are familiar with the concept of energy conservation. What happens to all that potential energy lost when it's dropped?
  4. Nov 30, 2008 #3
    oh ok, does that mean that the kinetic energy will be the same as the loss of potential energy then? But still, how do i work out the speed and momentum?
  5. Nov 30, 2008 #4
    Right, you now have KE before impact, and that KE = 1/2mv^2...
  6. Nov 30, 2008 #5
    Thanks alot! think ive done it now!
  7. Jan 14, 2010 #6
    Conservation of Energy is easy. But to clarify, you can still calculate the velocity without it.
    The egg has been dropped => initial velocity is zero!
    All freely falling bodies accelerate at g which is 9.8m/s2
    The body traveled 1.5m before hitting the ground.
    You will need two equations and work a little more.
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