Hey yaar, it's a matter of frame of refernce.If u r in the lift, then u will see it falling with an acc. of g+a bcoz u r going up with acceleration a & it is falling with acceleration g. Now if u r standing at the ground, then U will see the ball falling with acceleration g. Answer given is g bcoz ground frame is inertial whereas lift frame is non inertial.
Plz Plz Rate me if satisfied......... Nudge me if not satisfied........... & yes..... Happy independence day!!!!
Next ISSAC NEWTON....
...student of NIT , allahabad......