(a)[1]
What does elastic potential energy mean?
(b)
A spring is stretched by applying a force. Fig. 4.1 shows how the force $F$ varies with extension $x$ for values of $x$ from $20\,\text{cm}$ to $40\,\text{cm}$.
(b(i))[2]
Use data from Fig. 4.1 to demonstrate that the spring obeys Hooke’s law for this range of extensions.
(b(ii).1)[2]
Use Fig. 4.1 to find the spring constant.
(b(ii).2)[3]
Use Fig. 4.1 to find the work done in stretching the spring from $x = 20\,\text{cm}$ to $x = 40\,\text{cm}$.
(c)[1]
In (b), a force is applied to the spring to produce an extension of $50\,\text{cm}$. State how you would check that the spring has not exceeded its elastic limit.