A machine is used to lift a load of 20 N through a height of 10m. if the efficiency of the machine is 40%; how much work is done?

A. 80 J
B. 500 J
C. 300 J
D. 120 J

Correct Answer:

Option B – 500 J

Explanation

Efficiency = work output/work input×100

= 40 = (20×10)/ x 100
= 500J