The greatest height to which a boy can throw a stone is (h). What will be the greatest distance on horizontal surface upto which the boy can throw the stone with the same speed ? Neglect the air friction.

Explanation

Maximum beight attained, ` H= (u^2 sin^@ theta)/ (2 g)`
(H) will be maximum, when sin ` theta =1 or theta -90^@`
:. ` H_max) = (u^2/(2 g) =h` (given)
Horizontal range will be maximum if angle of projection is ` 45^@` will the horizontal.
Max. Horizontal ramge,
`R_(max) =(u^2sin 2 xx 45^@)/g = u^2 /g =2 (u^2/(2 g)) =2h`.