Question

A mechanic uses a chain and block to lift a 875-kg engine 4.00 m to the top of the garage. The downward force in the chain over the 4.00 m distance is 5.00 x 10^4 N.
A) Calculate the work done in raising the motor
B) How much useful work was done?
C) What is the efficiency of the chain and block pulley in raising the motor?

Answer 1

work done = force * distance = 50,000*4 = 200,000 Joules

useful work= m g h = 875*9.81*4 =34,335 J

eff = 100 * 34335/200000 = 17.2%

Answer 2

3500J