Question

A crane lifts a concrete block, whose weight is 60,000N to a height of 20m in 30s.
What useful power is achieved by the crane?

A.100 W
B.4000 W
C.40,000 W
D.90,000 W

Answer 1

Answer:

C

Explanation:

Power formula is power=work(joules)/time(seconds). the Work formula is force (newtons) times the distance from the starting point. Calculate work first: 60,000N x20m = 1,200,000 joules. Then plug into power formula: 1,200,000j/ 30 seconds= 40,000 W