The elevator shown in figure is descending with an acceleration of $2 \mathrm{m} {\mathrm{s}}^{-2}$. The mass of the block $A$ is $0.5 \mathrm{kg}$. What force is exerted by the block $A$ on the block $B$?

A pendulum bob of mass $50 \mathrm{g}$ is suspended from the ceiling of an elevator. Find the tension in the string if the elevator

$\left(a\right)$ goes up with the acceleration $1.2 \mathrm{m} {\mathrm{s}}^{-2}$,

$\left(b\right)$ goes up with deceleration $1.2 \mathrm{m} {\mathrm{s}}^{-2}$,

$\left(c\right)$ goes up with a uniform velocity,

$\left(d\right)$ goes down with the acceleration $1.2 \mathrm{m} {\mathrm{s}}^{-2}$,

$\left(e\right)$ goes down with the deceleration $1.2 \mathrm{m} {\mathrm{s}}^{-2}$ and 

$\left(f\right)$ goes down with uniform velocity.

A person is standing on a weighing machine placed on the floor of an elevator. The elevator starts going up with some acceleration, moves with uniform velocity for a while, and finally decelerates to stop. The maximum and the minimum weights recorded are $72 \mathrm{kg}$ and $60 \mathrm{kg}$. Assuming that the magnitudes of the acceleration and the deceleration are the same, find

(a) the true weight of the person,

(b) the magnitude of the acceleration. Take $g=9.9 \mathrm{m} {\mathrm{s}}^{-2}$.

A block of $2 \mathrm{kg}$ is suspended from the ceiling through a massless spring of spring constant $k=100 \mathrm{N} {\mathrm{m}}^{-1}$. Suppose the ceiling is that of an elevator which is going up with an acceleration of $2.0 \mathrm{m} {\mathrm{s}}^{-2}$. What is the elongation of the spring? If another $1 \mathrm{kg}$ is added to the block, what would be the further elongation?