$A$ body of mass $2\, kg$ is hung on a spring balance mounted vertically in a lift. If the lift moves up with an acceleration equal to the acceleration due to gravity $g$,the reading on the spring balance will be .......... $kg$.

$A$ simple pendulum is attached to a block which slides without friction down an inclined plane $ABC$ having an angle of inclination $\alpha$ as shown below. While the block is sliding down,the pendulum oscillates in such a way that at its mean position,the direction of the string is

In an elevator moving vertically up with an acceleration $g$,the force exerted on the floor by a passenger of mass $M$ is

The free surface of oil in a tanker,at rest,is horizontal. If the tanker starts accelerating,the free surface will be tilted by an angle $\theta$. If the acceleration is $a \ m/s^2$,what will be the slope of the free surface?

$A$ 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 $(g = 9.8 \, m/s^2)$:

$A$ ball is dropped from an elevator moving upward with acceleration '$a$' by a boy standing in it. What is the acceleration of the ball with respect to the boy and the ground respectively? [Take upward direction as positive]