^Springs

1. Spring force does -ve work when we expand or stretch & +ve work when the spring force restores itself from extended or stretched positions.

2.Spring store energy called elastic potential energy whether expanded or stretched from relaxed state.

3.If a block of mass ‘m’ is released on a spring of stiffness constant ‘k’ from a height ‘h’ compresses it by amount  ‘x’ , then: mg (h + x) =