Discuss friction at atomic level.

Find the value of $T_1$ and $T_2$ in the given arrangement.

The mass of an elevator is $800 \mathrm{kg}.$ Calculate the magnitude of tension produced in the cable of the elevator when

$\left(\mathrm{i}\right)$ It is stationary.

$\left(\mathrm{ii}\right)$ It is ascending with an acceleration of $4 \mathrm{m}{ \mathrm{s}}^{-2}.$

$\left(\mathrm{iii}\right)$ It is descending with same acceleration. (Take $g=10 \mathrm{m}{ \mathrm{s}}^{-2})$