$A$ man of mass $60\, kg$ records his weight on a weighing machine placed inside a lift. The ratio of weights of the man recorded when the lift is ascending with a uniform speed of $2\, m/s$ to when it is descending with a uniform speed of $4\, m/s$ will be:

$A$ thief stole a box full of valuable articles of weight $W$ and while carrying it on his back,he jumped down a wall of height $h$ from the ground. Before he reached the ground,he experienced a load of:

$A$ man of mass $60 \ kg$ is standing in a lift moving up with a retardation of $2.8 \ ms^{-2}$. The apparent weight of the man is (in $N$)

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

The minimum acceleration that must be imparted to the cart in the figure so that the block $A$ will not fall (given $\mu$ is the coefficient of friction between the surfaces of the block and the cart) is given by

$A$ metallic rod of length $L$ and mass $M$ is moving under the action of two unequal forces $F_1$ and $F_2$ (directed opposite to each other) acting at its ends along its length. Ignore gravity and any external magnetic field. If the specific charge of electrons is $(e/m)$,then the potential difference between the ends of the rod in steady state must be: