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!

Homework Help: Kinetic Energy of diver

  1. Oct 4, 2004 #1
    Kinetic Energy, Help!!!

    A 66.0 kg diver is 4.90 m above the water, falling at speed of 8.20 m/s. Calculate her kinetic energy as she hits the water. (Neglect air friction)

    Then the problem hints:Use conservation of mechanical energy.

    So i'm thinking that conservation is K_f+U_f=K_i+U_i but there must something wrong with my calculations>
    K=1/2(m*v^2) and U=mgh right?
    Last edited: Oct 4, 2004
  2. jcsd
  3. Oct 4, 2004 #2
    ok let's say that delta (the triangle) is represented by d in my calcultions

    dK + dU = 0 conservation of energy

    KE (final) - KE (Initial) + PE (Initial) - PE (final) = 0

    sinceu want a value for KE final

    PE (final) = m g (0) = 0 becuase as diver hits water height is zero

    KE final = PE (initial) + KE (initial)

    now sub in and see waht you get
  4. Oct 4, 2004 #3
    From KE_final=PE(initial)+KE(initial) i get:
    (66.0)(9.8)(4.90)+1/2(66.0)(8.20^2)= 5388.2 and it was right thanxs a lot
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook