SSC JE Mechanical Engineering 2017 Set 4 Paper

Definition of rate change of momentum:
The rate of change of momentum, i.e. the no. of kg m/sec absorbed per second is simply the external force.
$\mathit{F}=\frac{\mathrm{\Delta }\mathit{P}}{\mathrm{\Delta }\mathit{t}}=\frac{\mathit{m}\mathrm{\Delta }\mathit{v}}{\mathrm{\Delta }\mathit{t}}$
Its direction is always along the applied force.