The ratio of the weight of a man in a stationary lift to his weight in a lift moving downwards with an acceleration '$a$' is $3:2$. Then '$a$' = . . . . . . .

$A$ man of mass $75\, kg$ is standing in an elevator which is moving with an acceleration of $5\, m/s^2$ in the upward direction. The apparent weight of the man will be ........... $N$ $(g = 10\, m/s^2)$.

The weight of a man in a lift moving upward is $608 \ N$,while the weight of the same man in the lift moving downward with the same acceleration is $368 \ N$. His normal weight is ............ $N$.

$A$ man of mass $80\ kg$ is standing inside a lift moving upward with a uniform velocity of $4\ m/s$. Then,the apparent weight of the person will be:

The readings shown in two extended spring balances,$S_1$ and $S_2$,are $60\,kg$ and $30\,kg$ respectively. The lift is accelerating upward with an acceleration of $10\,m/s^2$. The mass $m$ is stationary with respect to the lift. Then the mass of the block will be ......... $kg$. (Take $g = 10\,m/s^2$)

$A$ rough vertical board has an acceleration $a$ so that a $2 \ kg$ block pressing against it does not fall. The coefficient of friction between the block and the board should be