Question

The spring constant of spring is 100 N/m. the potential energy stored in spring is

Answer 1

Elastic Strain Energy = (1/2)kx^2 where k is the spring constant and x is the extension to work out the extension do $\frac{20N}{100N{m}^{-}1}=0.2m.$
now we have our variables put them into the formula
$\left(\frac{1}{2}\right)\times 100N{m}^{-1}\times 0.2m^2=2J$ while it is a form of energy so the units are obviously Joules we can work it out that they are Joules our units in the equation are Nm^-1 * m^2 which simplifies to Nm which using the formula Work = Force * Distance and given Work has unit Joules then Newtons*Metres = Joules