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: Energy Equation problem.

  1. Feb 28, 2007 #1
    The question I have is trying to solve the final velocity in an energy equation that goes like this: 0.5mv^2=0.5mv^2+mgy (The final velocity being on the LS).

    I'm not given the mass of the skier going down the hill so I divide to cancel the mass out. I then rearrange to get Vf^2 = V^2+gy. I've pretty much nailed it down to a simple algebra problem but I can't see what's wrong!

    Oh, I might add that I always plug numbers in before rearranging equations but my teacher doesn't like me doing that.
     
    Last edited: Feb 28, 2007
  2. jcsd
  3. Feb 28, 2007 #2

    PhanthomJay

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    You cancelled out the 'm's' just fine, but what you're left with is
    [tex]0.5V_f^2 = 0.5V_o^2 + gy [/tex] you left out that 0.5 factor.
    BTW, I always plug in numbers before rearranging equations. It sometimes leads to round off errors, but it sure makes the algebra a lot simpler and less confusing, because it's generally much easier to deal with numbers rather than letters, but don't tell teacher I said that!
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook