Question

An elastic string of length 20cm extends to 24cm when it supports a weight of 50N. Calculate the energy stored in the string.

Answer 1

k = 50/.04 N/m
E = 1/2 kx^2 J

Answer 2

Extension= final length- original length
Extension=24cm-20cm
Extension=4cm
Remember F = Ke
Therefore 50N = K ×4
Then K = 50/4 =12.5N/m
Then finally energy stored in a spring = 1/2Ke*2
Energy=1/2×12.5 ×4×4
Energy= 100 joules