A stone is projected at an angle 300 with the horizontal  with a velocity 20 m/s from the top of a building 15 m high . The velocity with which it will hit the ground is

horizontal component of the velocity of the stone remains constant  20 cosθ=103m/s but initial vertical component of velocity is 20sin 300=10m/s      and final vertical velocity  will be vy=uy2+2gy   =102+21015=20m/s resultant velocity 1032+202=700=107 m/s