Question
A body is projected with velocity u at angle θ with vertical. At what height will it strike the wall, r distance away from the point of projection?
Solution
Consider a body which is projected from O in XY plane with velocity 'u' at angle θ with vertical, and
The body is projected at an angle α = 90°–θ with the horizontal.
Let the body strike the wall at height h.
So, co-ordinates of point P where the projectile hits the wall are ↔ (r,h).
Equation of trajectory is given by,
[∵ 
]
Since
lies on trajectory,
The body is projected at an angle α = 90°–θ with the horizontal.
Let the body strike the wall at height h.
So, co-ordinates of point P where the projectile hits the wall are ↔ (r,h).
Equation of trajectory is given by,
[∵ ] Since
lies on trajectory, ∴ 
,
is the height at which the body will strike the wall.
, is the height at which the body will strike the wall.
