Q.A spring stretches by $2\ \text{cm}$ when a force of $8\ \text{N}$ is applied to it. Find the force constant of the spring, and write the restoring force acting on the spring when it is displaced by $x$ from its natural length.

By Hooke's law, $F=kx$ in magnitude, so the force constant is

When this spring is displaced by a general distance $x$ from its natural length, the restoring force acting on it, directed back towards the natu …

Apply $k=F/x$ using the given force and extension, then write the general restoring-force l …

• Forgetting to convert the extension from centimetres to metres before dividing, which would give a force constant $100\times$ too small. …