Recent content by waqar

No external force is applied. The mass was left to fall freely, hanging by the spring. The analysis is made when system has now come to rest. That's when we can take F_g=F_s and also complete energy transfer from gravitational to elastic.

The spring is first relaxed at its lower end h_1, that's when we attached mass m to itand let it fall freely and come to rest. Now by Force analysis we can show that in final position of mass the forces of gravity and restoring force from spring are balanced. i.e. F_g=F_s which yields x=-mg/k...