From a motorboat moving downstream with a velocity `2 m//s` with respect to river, a stone is thrown. The stone falls on an ordinary boat at the instant when the motorboat collides with the ordinary boat. The velocity of the ordinary boat with repsect to the river is equal to zero. The river flow velocity is given to be `1 m//s`. The initial velocity vector of the stone with respect to earth is :-

Options

A. `2i+20j`
B. `3i+40j`
C. `3i+50j`
D. `2i+50j`

Answer

C

Explanation

Time of collision of two boat `=20//2=10` sec. As given in question i.e. the time of flight of stone is also equal to `10` sec. so vertical component of stone initially is `50 m//s` and the horizontal component w.r.t. motorboat equals to `2 m//s`.
Hence `vec(v)_(BG)=3hat(i)+50hat(j)`