Question

A 1.75 kg object is initially at rest on a horizontal frictionless surface and is attached to an initially unstretched spring with a force constant of 50 N/m and negligible mass. A constant horizontal force of 338.75 N is applied to the object. Determine the following when the object has slide a distance 0.75 m:
the work done by the applied force  J,
the energy stored in the spring  J,
the object's final kinetic energy  J, and
the object's final speed  m/s.

Answer 1

The work done by the external applied force will be equal to sum of increase in potential energy and increase in kinetic energy of the system of block and the spring. We use this to find the required solution as shown below