Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Hey whats mechanical energy got to do with it? +__+ yeesh

  1. Nov 23, 2004 #1
    a 55 kg high jump athlete leaps into the air in attempt to clear the bar, at the top of the leap the athlete has a total mechanical energy of 3x10 to the power of 10 joules and is moving at 8.33m/s.

    Calculate the gravitational potentional energy.

    what the hell? how do i get my height?
    i have my mass which is 55

    and gravity which is 9.8 soo what am i supposed to do?

    how do i use mechanical energy too is it also work? how do i use that to get

    answer? lol so confusing someone help please ^^
     
  2. jcsd
  3. Nov 23, 2004 #2
    Well the total mechanical energy is equal to the sum of the kinetic energy and the potential energy, i.e:

    3x10^10=1/2 m v^2 +mgh
    so mgh=3x10^10 -1/2(55)(8.33)^2

    Hope that helps
    Ray
     
  4. Nov 23, 2004 #3
    lol thanks its for a friend i've only just learned conservation of energy but mechanical energy term really threw me off
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook