Question

Work of 3 Joules is done in stretching a spring from its natural length to 20 cm beyond its natural length. What is the force (in Newtons) that holds the spring stretched at the same distance (20 cm)?

Answer 1

If the work done is 3 Joules then that means the potential energy held by the spring is also 3 Joules. \[PE=(1/2)kx ^{2}\]
x=.2m so you can now get the spring constant k

F=kx you have k and x so you can now get the Force. Goodluck! :D