Anonymous
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!

Relevance
• 10 years ago

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