Question

The unstretched length of a piece of elastic rubber is 5cm a force of 9N is required to stretch if by 1cm.what amount of work will be done to stretch the rubber from a length of 12cm to 8cm if the rubber remained within the elastic limit?

Answer 1

k =9 N/.01 meter = 900 N/m

if you mean from 8 to 12

potential energy at 12 = (1/2) k (.07)^2
potential energy at 8 = (1/2) k (.03)^2

subtract to get Joules required

Answer 2

Thanks