Question

A ball ,after having fallen from rest under the influence of gravity for 5 second,crashes a horizontal glass plate,there by losing 1/3 of its velocity.if it reaches the ground in 3 second,find the height of glass state from the ground

Answer 1

Velocity of ball after 5s
v = gt
v = 10 * 5
v = 50 m/s

Final velocity when it hits the ground
v = u + at
v = 50/3 + 10*3
v = 46.66 m/s

After losing 1/3rd velocity it falls height H
H = (v^2 - u^2) / (2g)
= (46.66^2 - (50/3)^2) / (2 * 10)
= 94.96 m

Glass is at height 94.96m from the ground.