Question

A stone is projected from ground and hits a smooth vertical wall after 1 sec. and again falls back on the ground. The time taken by stone to reach the ground after the collision is 3 secs. The maximum height reached by the same stone if the vertical wall were not to be present is. (g = 10 m/s2)

(A) 10 m

(B) 12.5 m

(C) 15 m

(D) 20 m

Answer 1

Correct option (D) 20 m

Explanation:

Time of flight of projectile depends on vertical component of velocity and not on the horizontal component. Collision of the stone with the vertical wall changes only the horizontal component of velocity of stone.

Thus the total time of flight in absence of wall is also T = 1 + 3 = 4sec