A boy thrown a ball into air at 45° from the horizontal to land it on a roof of a building of height H. If the ball attains maximum height in 2 s and lands on the building in 3 s after launch, then value of H i $s ________$ m.
(g = 10 m/s²)

Question

A boy thrown a ball into air at 45° from the horizontal to land it on a roof of a building of height H. If the ball attains maximum height in 2 s and lands on the building in 3 s after launch, then value of H i $s ________$ m.

(g = 10 m/s²)

G1 Physics · Accepted Answer

The ball reaches maximum height after 2 s. Therefore the initial vertical velocity component is uᵧ = gt(up) = 10×2 = 20 m/s. At time t = 3 s, the vertical displacement from the point of projection is H = uᵧt - ½gt². Hence, H = 20×3 - ½×10×3² = 60-45 = 15 m. Correct option: D.

A boy thrown a ball into air at 45° from the horizontal to land it on a roof of a building of height H. If the ball attains maximum height in 2 s and lands on the building in 3 s after launch, then value of H i s ________ m. (g = 10 m/s²)