If the earth stops rotating,the value of '$g$' at the equator will:

Which of the following is the evidence to show that there must be a force acting on the earth and directed towards the sun?

$A$ soft drink bottle is dropped by a waiter from the top of a hotel whose height is $100 \, m$. It takes $T$ seconds to reach the ground. Where will it be at $T/2$ seconds?

Choose the correct alternative:
$(a)$ Acceleration due to gravity increases/decreases with increasing altitude.
$(b)$ Acceleration due to gravity increases/decreases with increasing depth.
$(c)$ Acceleration due to gravity is independent of the mass of the earth/mass of the body.

Three students $A, B$ and $C$ were performing an experiment to establish the relation between the weight of a wooden block and the minimum force required to just move it on a horizontal surface. The experimental setup used by each is as shown in the figures given below.
The result obtained by them will be:

$A$ ball is dropped from a height of $20\, m$. $A$ second ball is thrown downwards from the same height after one second with initial velocity $u$. If both the balls reach the ground at the same time, calculate the initial velocity of the second ball. (Take $g = 10\, m s^{-2}$).