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: One more quick convervation of energy problem!

  1. Oct 10, 2008 #1
    1. The problem statement, all variables and given/known data

    A skier leaves a slope with an initial speed of 5 m/s. Her speed at the bottom of the slope is 13 m/s. What is the height of the slope?

    2. Relevant equations
    PE= mgh
    KE= 1/2mv^2


    3. The attempt at a solution

    PE + KE1 = KE2

    PE=KE2-KE1

    mgh = 1/2mv^2 -1/2mv^2

    gh = 1/2v^2 -1/2v^2

    h = 1/2mv^2 -1/2mv^2 / g

    when I plug everything in, I get 14.9

    the answer is 7.3


    what am I doing wrong?
     
  2. jcsd
  3. Oct 10, 2008 #2

    Hootenanny

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Where have these masses appeared from? If these masses are just a typo and you really used,

    h = (vi2 - vf2)/(2g)

    Then you have simply plugged the numbers in wrong.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook