A light vertical spring of force constant is fixed at its upper end to a rigid support
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A light vertical spring of force constant k is fixed at its upper end to a rigid support. A block of mass m is attached to its lower end and allowed to hang freely so that the system comes to rest at its equilibrium position where the spring is extended by x0 from its natural length.
Answer the following questions related to the energy changes in this arrangement:
(i) Define gravitational potential energy and elastic potential energy for this system, clearly stating the reference levels you choose.
(ii) The block is now very slowly lowered further by a distance x1 and then brought back slowly to the equilibrium position. Explain qualitatively how the gravitational potential energy, elastic potential energy and the total mechanical energy of the system vary during this process.
(iii) Starting from the equilibrium position, the block is pulled down an additional small distance and released from rest so that it executes vertical oscillations. Describe, with reasons, at which positions during one complete oscillation
(a) elastic potential energy is maximum,
(b) gravitational potential energy is maximum,
(c) kinetic energy is maximum.