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`)
2. The maximum height reached by ball, as measured from the ground would be

Options

A. 52 m
B. 31.25 m
C. 83.25 m
D. 63.25 m

Answer

C

Explanation

c. The height of the ball from ground at the time of projection is
52m. Maximum height from point of projection is
`h = (|vecv_(BG)|^2)/(2a_(BG)) = (25)/(2xx10) = 31.25m `
Required height = `52 + 31.25 = 83.25m` .