Q.

A ball projected from ground at an angle of 45° just clears a wall in front. If point of projection is 4 m from the foot of wall and ball strikes the ground at a distance of 6 m on the other side of the wall, the height of the wall is:

1 4.4 m  
2 2.4 m  
3 3.6 m  
4 1.6 m  

Ans.

(2)

As ball is projected at an angle 45° to the horizontal therefore Range =4H

or  10=4H⇒H=104=2.5 m

Height of wall PA=OAtanθ-12g(OA)2u2cos2θ

=4-12×10×1610×10×12×12=2.4 m