$A$ body is thrown up in a lift with a velocity $u$ relative to the lift,and the time of flight is found to be $t$. The acceleration with which the lift is moving up is:

$A$ boy having a mass equal to $40 \, kg$ is standing in an elevator. The force felt by the feet of the boy (apparent weight) will be greatest when the elevator $(g = 9.8 \, m/s^2)$:

$A$ smooth sphere of radius $R$ moves along a straight line with a constant acceleration $a = g$. $A$ particle is placed at the top of the sphere. It is released from there with zero velocity relative to the sphere. What will be its speed relative to the sphere as a function of the angle $\theta$ as the particle slides?

$A$ car is moving on a circular horizontal track of radius $10 \,m$ with a constant speed of $10 \,m/s$. $A$ bob is suspended from the roof of the car by a light wire of length $1.0 \,m$. The angle made by the wire with the vertical is (in rad)

$A$ person in an elevator accelerating upwards with an acceleration of $2\,ms^{-2}$,tosses a coin vertically upwards with a speed of $20\,ms^{-1}$. After how much time will the coin fall back into his hand? (Take $g = 10\,ms^{-2}$)

Cream gets separated out of milk when it is churned,it is due to