Question

40.) A man of weight 60 kg wt takes a body of
mass 15 kg at a height 10 m on a building in
3 minutes. The efficiency of man is
(a) 10%
(b) 20%
(c) 30%
(d) 40%​

Answer 1

Explanation:

w = 60kg

m = 15kg

h = 10m

g = 10m/s

work done = mgh

15×10×10= 1500

work done = (M+m)gh

(60+15)10×10

7500

Efficiency = 1500/7500 ×100

=20%

option (b)