The gradient of the line \(\frac{\text{F}}{\text{e}}\) is the spring constant, k. Key fact The gradient of the graph of force F, (y-axis), and extension e, (x-axis), is equal to the spring constant k.

A spring has a spring constant, k, of 3 N/m. It is stretched until it is extended by 50 cm. Calculate the elastic potential energy stored by the spring, assuming it is not stretched beyond the ...