$A$ man is standing on a weighing machine placed in a lift. When stationary,his weight is recorded as $40 \, kg$. If the lift is accelerated upwards with an acceleration of $2 \, m/s^2$,then the weight recorded in the machine will be .......... $kg$ $(g = 10 \, m/s^2)$.

$A$ man weighing $75 \,kg$ is standing in a lift. The weight of the man standing on a weighing machine kept in the lift when the lift is moving downwards freely under gravity is

$A$ very broad elevator is going up vertically with a constant acceleration of $2\,m/s^2$. At the instant when its velocity is $4\,m/s$,a ball is projected from the floor of the lift with a speed of $4\,m/s$ relative to the floor at an elevation of $30^{\circ}$. The time taken by the ball to return to the floor is $..............\,s$ $(g=10\,m/s^2)$.

$A$ 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:

In the figure shown,$P$ is a plate on which a wedge $B$ is placed,and on $B$ a block $A$ of mass $m$ is placed. The plate is suddenly removed and the system of $B$ and $A$ is allowed to fall under gravity. Neglecting any force due to air on $A$ and $B$,the normal force on $A$ due to $B$ is

$A$ boy whose mass is $50\,kg$ stands on a spring balance inside a lift. The lift starts to ascend with an acceleration of $2\,m/s^2$. The reading of the machine or balance $(g = 10\,m/s^2)$ is ........ $kg$.