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Anonymous asked in Science & MathematicsPhysics · 10 years ago

Physics homework help..very appreciated?

A champion weight lifter did 1.10 x 10^4 J of work on a set of barbells weighing 3680N. How much gravitational potential energy did the barbells have at the maximum height of the lift?

please EXPLAIN THOROUGHLY, i am confused and I can't find much help. thanks a ton in advance!

2 Answers

  • 10 years ago
    Favorite Answer

    The work done in lifting a weight mg to a height h equals

    W = mg h

    We know work (1.10 10^4 J) and force (3680 N), so the height over which he lifted is

    W = F h

    h = W/F

    h = 1.10 10^4 J / (3680 N) = 2.99 m

    At that height, the mass of the barbells has potential energy

    E = m g h

    but this gives 1.10 10^ J again!

    To cut a log story short: The work the champion did goes into gravitational potential energy (kinetic energy is zero at the bottom and highest point) . It is just a matter of conservation of energy....

  • Anonymous
    10 years ago

    1.1 * 10^4 because all of the kinetic energy would be converted to GPE at the highest point in the lift

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