Write the expression for the restoring force produced in a spring when a body attached to its end is pulled down by a small displacement $x$.

(N/A) When a body of mass $m$ is attached to a spring of spring constant $k$ and is pulled down by a small displacement $x$ from its equilibrium position,the spring exerts a restoring force $F$ that acts in the direction opposite to the displacement.
According to Hooke's Law,the magnitude of the restoring force is directly proportional to the displacement $x$.
Mathematically,the restoring force is given by $F = -kx$,where the negative sign indicates that the force is directed towards the equilibrium position,opposing the displacement.