When jet liquid strikes a fixed or moving surface it exerts thrust on it due to rate of change of momentum `F=(rhoAv_(0))v_(0)-(rhoAv_(0))v_(0)costheta=rhoAv_(0)^(2)[1-costheta]`
If surface is free and starts moving due to thrust of liquid then at any instant the above equation gets modified based on relative change of momentum with respect to surface let any instant the velocity of surface is u, then above equation becomes `F=rhoA(v_(0)-u)^(2)[1-costheta]`
Based on above concept in the below given figure if the cart is frictionless and free to move in horizontal direction then answer the following given corss section area of jet `=2xx10^(-4)m^(2)` velocity of jet `v_(0)=10m//s` density of liquid `=1000kg//m^(3)` mass of cart M=10kg
Q. Initially (t=0) the force on the cart is equal to

Options

A. 1.6s
B. 2s
C. 3.2s
D. 4s

Answer

A