JEE Mains Previous Years Questions with Solutions

4.5
star star star star star
1

AIEEE 2002

A lift is moving down with acceleration $a.$ A man in the lift drops a ball inside the lift. The acceleration of the ball as observed by the man in the lift and a man standing stationary on the ground are respectively
A
$g,g$
B
$g-a, g-a$
C
$g-a, g$
D
$a, g$

Explanation

Let acceleration of ball = ${\overrightarrow a _b}$ and acceleration of man is = ${\overrightarrow a _m}$

With respect to the man standing in the lift, the acceleration of the ball

${\overrightarrow a _{bm}} = {\overrightarrow a _b} - {\overrightarrow a _m}$

$\Rightarrow {a_{bm}} = g - a$

Where $a$ is the acceleration of the man as the acceleration of the lift is $a$.

With respect to the man standing on the ground the acceleration of the ball

${\overrightarrow a _{bm}} = {\overrightarrow a _b} - {\overrightarrow a _m}$

$\Rightarrow {a_{bm}} = g - 0$

$= g$