Question

please solve this first

Answer 1

Concept :-Lift is accelerated in upward direction. hence, non- inertial frame .
so, Puedo force concept should apply here.

acceleration of lift = f (↑)
so, puedo accⁿ = f ( ↓)
accⁿ due to gravity = g (↓)

A ball is thrown vertically upward with velocity V relative to lift .

use, formula ,
Srel = Sorel + Urel.t + 1/2arel.t²
where ,
Srel = final position
Sorel = initial position
Urel = initial velocity of ball with respect to lift .
arel = acceleration of ball with respect to lift .

when ball comes in his hand it means
final position = initial position
Srel = Sorel

Vrel = V (↑)
arel = -(f + g) (↑)

now,
Srel = Sorel + Vt + 1/2{-(f + g)}t²
Vt = 1/2(f + g)t²
V = (f + g)t/2
hence, proved //

Answer 2

this is your answer ✔️✔️✔️