Question

A.) A weight lifter bench presses 185 lbs, lifting the weights from chest position (2.17 feet above ground), 1.80 feet above with extended arms. How much work has been performed?

B.) What energies (if any) are present at initial chest position?

C.) What energies are present (if any) at final position while weights are held briefly?

D.) How much energy (if any) is present at final position while weights are held briefly?

E.) Assuming that no nonconservative forces act on the system, what could you conclude between the initial and final energies of motion in this circumstance?

F.) Given the information on A and E, find the final velocity that weights are been lifted with.

Answer 1

Here we apply definition of work done and definition of gravitational potential energy and work kinetic energy theorem.