Question

the 7 question. I want to know the steps

Answer 1

Answer by:- priyanka

Given, the work required to stretch the spring through 0.1m = 20 J. 
Work done, W1 = F * x = (1/2 * kx) * x =1/2*kx^2 = 0.5*k*0.01 = 20 J 
Therefore, k = 20/0.005 = 4000N/m 
When the spring is further stretched through 0.1 m that is, y = 0.2 
Work done, W2 = ½*(y^2 - x^2) 
=0.5*4000(0.2^2 - 0.1^2) 
= 0.5*4000*(0.04-0.01) 
= 60 J