A ball is projected from the ground at angle θwith horizontal. After 1s, it is moving at angle 45∘ with horizontal and after 2s it is moving horizontally. What is velocity of projection of the ball?
10√5 m/s
tanθ=VyVx=u sin θ−gtu cos θGiven α=45∘ when t=1 and, α=0 when t=2ucosθ=usingθ−g.....(1), 2g=usinθ.....(2)from (1) and (2)usinθ=2g and ucosθ=gu=√5g=10√5 m/s