$A$ weight is suspended from the ceiling of a lift by a spring balance. When the lift is stationary,the spring balance reads $W$. If the lift suddenly falls freely under gravity,the reading on the spring balance will be

$A$ $60\, kg$ man stands on a spring scale in a lift. At some instant,he finds the scale reading has changed from $60\, kg$ to $50\, kg$ for a while and then comes back to the original mark. What should we conclude?

$A$ rocket is moving in a gravity-free space with a constant acceleration of $2 \ ms^{-2}$ along the $+x$ direction (see figure). The length of a chamber inside the rocket is $4 \ m$. $A$ ball is thrown from the left end of the chamber in the $+x$ direction with a speed of $0.3 \ ms^{-1}$ relative to the rocket. At the same time,another ball is thrown in the $-x$ direction with a speed of $0.2 \ ms^{-1}$ from its right end relative to the rocket. The time in seconds when the two balls hit each other is:

$A$ car is moving with a constant speed of $20\,m/s$ on a circular horizontal track of radius $40\,m$. $A$ bob is suspended from the roof of the car by a massless string. The angle made by the string with the vertical will be: (Take $g = 10\,m/s^2$)

$A$ stunt man jumps his car over a crater as shown (neglect air resistance).

The spring balance inside a lift suspends an object. As the lift begins to ascend,the reading indicated by the spring balance will