Question

How to find the force constant of a helical spring by plotting graph between load and extension?

Answer 1

Force constant is expressed as force per unit displacement.  

Plot a graph between F and l along X- and Y-axis respectively. The graph would result in a straight line as which shoes linearity in property. It shoes a directly proportional relationship between two quantities. As the load increases then the extension of the spring also increases proportionally.

From the graph,

$k=\frac{F}{l}$  

$=\frac{150}{1.5}$  

=100g/cm