Question $2$:

$(4$ marks$)$

A horizontal water jet $(=1000k\frac{g}{m^3})$ with a velocity of $10\frac{m}{s}$ hits perpendicularly on a vertical flat plate attached to a vehicle and splashes off in a sideways direction $($i$.$e$.,$ all initial horizontal momentum is $100\%$ transferred to the plate$).$ The vehicle is moving toward the oncoming water jet with a velocity of $5\frac{m}{s}.$ If$,$ before the vehicle started to move, a force of $10$ N was required to maintain the vehicle stationary $($i$.$e$.$ at equilibrium with the force of the jet$),$ how much force is required to move the vehicle toward the water jet at $5\frac{m}{s}?$ Assume that the jet is uniform, and that the vehicle experiences negligible friction.