Question

Two earthworms climb over a rough thin wall of an earthen pot 10 cm high placed in a lawn.

One of the worm is 20 cm long and other is only 10 cm long and mass of both earthworms is 20 g. 

Ratio of work done by worms when they crosses half of their length across top of the wall is 

(a) 1 : 1 

(b) 2 : 3 

(c) 2 : 1 

(d) 1 : 2

Answer 1

Correct option is (b) 2 : 3

For 10 cm worm centre of mass is raised upto height of 7.5 cm, while for 20 cm worm height of centre of mass is 5 cm from ground. 

So, ratio of work done by 20 cm worm to that of 10 cm worm is