Due to the presence of air resistance, if a body dropped from a height of $20 \ m$ reaches the ground with a speed of $18 \ m/s$, then the time taken by the body to reach the ground is nearly (in $s$)

Galileo's law of odd numbers: "The distances traversed, during equal intervals of time, by a body falling from rest, stand to one another in the same ratio as the odd numbers beginning with unity [namely, $1: 3: 5: 7 \ldots$]". Prove it.

$A$ body thrown vertically upwards from the ground reaches a maximum height $H$. The ratio of the velocities of the body at heights $\frac{3H}{4}$ and $\frac{8H}{9}$ from the ground is

$A$ particle is thrown with any velocity vertically upward. The distance travelled by the particle in the first second of its descent is:

$A$ man in a balloon rising vertically with an acceleration of $4.9 \, m/s^2$ releases a ball $2 \, s$ after the balloon is let go from the ground. The greatest height above the ground reached by the ball is .......... $m$ :-

$A$ body is projected vertically upwards. The times corresponding to a specific height while ascending and while descending are $t_{1}$ and $t_{2}$ respectively. Then the velocity of projection is (where $g$ is acceleration due to gravity).