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 $s$)

$A$ particle is projected upwards. The times corresponding to height $h$ while ascending and while descending are $t_1$ and $t_2$ respectively. The velocity of projection will be

$A$ body is projected vertically upwards. It reaches a point at a height $h$ above the point of projection after some time with a speed of $8 \,m/s$. The maximum height reached by the body is (Acceleration due to gravity $g = 10 \,m/s^2$). (in $m$)

$A$ juggler tosses a ball up in the air with initial speed $u$. At the instant it reaches its maximum height $H$,he tosses up a second ball with the same initial speed. The two balls will collide at a height:

What is the initial velocity of an object falling freely (in $m/s$)?

$A$ body falls from rest in the gravitational field of the earth. The distance travelled in the fifth second of its motion is ......... $m$ $(g = 10\,m/s^2)$.