Question

Hailstones falling vertically with a speed of 10 m/s, hit the wind screen (wind screen makes an angle 30° with horizontal) of a moving car and rebound elastically. find the velocity of the car driver finds the hailstones rebound vertically after striking.

Answer 1

The velocity of the car is 10√3 m/s

Answer 2

As given the situation, the hailstone is falling vertically at an angle of 90 degrees to the moving car and strikes at an angle of 30degree with the horizontal of the moving car. It is then rebounded elastically, therefore, the given figure can be made which describes the present situation.

Therefore V is the velocity to be calculated which is the sum of the component of Vc and VH, where Vc is the velocity of the car relative to the ground and VH is the velocity of hailstone in relation to the ground.

Therefore,

V=Vc-VHcot30°

$=10\sqrt { 3 }$ metre per sec.