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: Wagon velocity physics problem

  1. Nov 21, 2005 #1
    There's a wagon standing on a hill
    The Height :0,81m
    When v1 = 0m/s then v2 = 4m/s when the wagon has rolled down the slope.
    What is the velocity when the startvelocity is 2m/s ...

    How do I do this...

    I've tried many things but I don't know the mass so how should I do?

    Please help
     
  2. jcsd
  3. Nov 21, 2005 #2
    try using potential and Kinetic energy equations
     
  4. Nov 21, 2005 #3
    Is this right?

    Is this right then... I take 2m/s which is v1 and put in in kinetical energy equation and take out v^2= Sqrt 2*g*h = 4,45 which is the right answer but I don't seem right it must be harder than that
     
  5. Nov 21, 2005 #4
    Energy is conserved;
    Eintial = Efinal
    Pei + Kei = Pef + Kef
    mgh + 1/2mvi^2 = 1/2mvf^2

    or from equations of motion:
    v^2 = v0^2 + 2*a*x where x is h

    both result in the same answer.
     
    Last edited: Nov 21, 2005
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook