1. Limited time only! Sign up for a free 30min personal 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!

Conservation of Energy

  1. Jun 15, 2014 #1
    1. The problem statement, all variables and given/known data

    A shot putter throws her shot. At the moment the 4.00 kg weight leaves her hand, it as a velocity of 14.0 m/s and is 2.00 m above the ground. The weight reaches a maximum height of 6.50 m above the ground before falling back down.

    What is the magnitude of the weighted ball's velocity at the peak of its trajectory?

    2. Relevant equations

    Ek = (0.5)(m)(v2)
    Ep = (m)(g)(h)

    3. The attempt at a solution

    (0.5)(m)(v2) initial + (m)(g)(h) initial = (0.5)(m)(v2) final+ (m)(g)(h) final

    (0.5)( 14 m/s)2 + (2 m)(9.8 m/s2) = (0.5)(v2) + (9.8 m/s2)(6.5 m)

    Vpeak = 5.19 m/s

    I don't know if this is correct... isn't the velocity at the peak supposed to be zero as all the energy is potential.
     
  2. jcsd
  3. Jun 15, 2014 #2

    PhysicoRaj

    User Avatar
    Gold Member

    Yes, but when? What type of motion are you dealing with?
     
  4. Jun 15, 2014 #3

    PhysicoRaj

    User Avatar
    Gold Member

    Hint: you mentioned a shot put.
     
  5. Jun 15, 2014 #4

    Doc Al

    User Avatar

    Staff: Mentor

    Your approach is correct, but I don't see how you got that answer. Resolve for the velocity.

    Note that the weight is not thrown vertically.
     
  6. Jun 15, 2014 #5
    The peak velocity is 10.38 m/s.
     
  7. Jun 15, 2014 #6

    Doc Al

    User Avatar

    Staff: Mentor

    That's better.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted