$A$ particle is thrown vertically upwards with a velocity of $4\,ms^{-1}$. The ratio of its accelerations after $1\,s$ and $2\,s$ of its motion is

$A$ food packet is dropped from a helicopter rising up with a velocity of $4 \, ms^{-1}$. The velocity of the packet after $3 \, s$ will be ....... $ms^{-1}$. (in $.4$)

$A$ ball is thrown vertically upward. It has a speed of $10 \; m/s$ when it has reached one-half of its maximum height. How high does the ball rise? (Take $g = 10 \; m/s^2$)

Water drops fall at regular intervals from a tap which is $5\,m$ above the ground. The third drop is leaving the tap at the instant the first drop touches the ground. How far above the ground is the second drop at that instant?

$A$ stone is dropped from the top of a tall building and after $2 \,s$ another stone is thrown vertically downwards with a velocity $5 \,m/s$ from the same point. The distance from the top of the building at which the second stone overtakes the first is . . . . . . $\left(g=10 \,m/s^2\right)$ (in $\,m$)

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 $s$)