An elevator without a ceiling is ascending up with an acceleration of `5 ms^-2.` A boy on the elevator shoots a ball in vertical upward direction from a height of 2 m above the floor of elevator. At this instant the elevator is moving up with a velocity of `10 ms^-1` and floor of the elevator is at a height of 50 m from the ground. The initial speed of the ball is `15 ms^-1` with respect to the elevator. Consider the duration for which the ball strikes the floor of elevator in answering following questions. (`g=10 ms^-2`)
3. Displacement of ball with respect to ground during its night would be

Options

A. 32.64 m
B. 2 m
C. 52 m
D. 30.64 m

Answer

D

Explanation

d. Displacement of floor of elevator in 2.13 s is
`s_1 = 10t + 1/2 xx 5 xx t^2 = 32.64m`
So displacement of ball w.r.t. ground.
`vecs_(BG) = vecs_(BE) + vecs_(EG) = -2+ 32.64 = 30.64m`.