$A$ rectangular box contains water. It is being pulled to the right with an acceleration $a$. Which of the following options shows the correct shape of the water surface?

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

An object of mass $5\, kg$ is attached to the hook of a spring balance and the balance is suspended vertically from the roof of a lift. The reading of the spring balance when the lift is going up with an acceleration of $0.25\, m/s^2$ is ......... $N$ $(g = 10\, m/s^2)$

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

What is weightlessness? Explain with examples.

$A$ coin is dropped in a lift. It takes time $t_1$ to reach the floor when the lift is stationary. It takes time $t_2$ when the lift is moving up with constant acceleration $a$. Then: