Question

A forklift is used to lift a large 704 kg crate a distance of 5.54 m in 6.12 s. What is the efficiency of the forklift if it takes a total of 8040 J/s of chemical energy in the form of burning fuel to complete this task?

Answer 1

$P_1=\frac{mgh}{t}=\frac{704\cdot 9.8\cdot 5.54}{6.12}=6250~W,$

$\eta=\frac{P_1}{P_2}=\frac{6250}{8040}=0.78=78\%.$