1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

2 Quck Questions on Work and Energy

  1. Jan 8, 2009 #1
    1. The problem statement, all variables and given/known data

    1. If a 0.2 kg ball is dropped from a height of 8 m, what is its kinetic energy when it hits the ground?


    2. Jane, looking for Tarzan, is running at top speed (4.6 m/s) and grabs a vine hanging vertically from a tall tree in the jungle. How high can she swing upward?

    2. Relevant equations
    Kinetic Energy = (1/2) mass*gravity*height
    Potential Energy= mass*gravity*height
    not sure if this equation is right.... distance=(1/2)(gravity)(time^2)
    Velocity= (change in distance)/time


    3. The attempt at a solution
    my work got deleted for both the question (error in webassign) and now I have no idea how I got the answers. (both wrong) But they were 9.5J for the first one and 14.2m for the second question.
     
  2. jcsd
  3. Jan 8, 2009 #2

    berkeman

    User Avatar

    Staff: Mentor

    Your KE equation is wrong. It's mixed up with the correct PE equation. Fix the KE equation, and you should get the correct answers.
     
  4. Jan 8, 2009 #3
    woops I had it actually I just wrote typed it out wrong it is (1/2)mv^2
     
  5. Jan 8, 2009 #4
    For part a, maybe im missing something, but did you say that your answer of 9.5J was correct? because im thinking otherwise unless im missing something very obvious.

    E(i)=E(f) ---> PE=KE in this case correct?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: 2 Quck Questions on Work and Energy
  1. Energy/Work Questions? (Replies: 5)

Loading...