A particle \(P\) of mass \(0.4\) kg is projected vertically upwards from horizontal ground with speed \(10\) m s\(^{-1}\).
- Find the greatest height above the ground reached by \(P\). [2]
When \(P\) reaches the ground again, it bounces vertically upwards. At the first instant that it hits the ground, \(P\) loses \(7.2\) J of energy.
- Find the time between the first and second instants at which \(P\) hits the ground. [4]