Question

A ball is dropped from an elevator moving upward with acceleration ‘a’ by a boy standing in it. The acceleration of ball with respect to [ Take upward direction positive ] (1) Boy is –g , (2) Boy is -( g+a) , (3) Ground is -g , (4) Both (2) &(3)

Answer 1

Answer:

(2) Boy is -( g+a)

Explanation:

When ball is dropped, it is in the free falling state and experiencing a gravitational acceleration (g).

But the boy moving upward with the acceleration (a) as mention in the question that upward direction is positive.

So, the acceleration of the ball with respect to the boy is = - (g+a)  

Where, minus sign shows that the elevator is moving against the gravity.

Answer 2

Answer:Both 2 and 3

Explanation:

The boy is in a non inertial frame of reference .So net acceleration wrt boy is-(g+a) we are including the pseudo force.

The ground is an inertial frame of reference so pseudo force is not included hence net acceleration wrt ground is-g