1 A particle, \(P\), of mass 2 kg moves in two dimensions. Its initial velocity is \(\binom { - 19.5 } { - 60 } \mathrm {~ms} ^ { - 1 }\).
- Calculate the initial kinetic energy of \(P\).
For \(t \geqslant 0 , P\) is acted upon only by a variable force \(\mathbf { F } = \binom { 4 t } { - 2 } \mathrm {~N}\), where \(t\) is the time in seconds.
- Find
- the velocity of \(P\) in terms of \(t\),
- the times when the power generated by \(\mathbf { F }\) is zero.