From the top of a tower,two stones,whose masses are in the ratio $1:2$,are thrown: one straight up with an initial speed $u$ and the second straight down with the same speed $u$. Neglecting air resistance,which of the following is true?

$P, Q$ and $R$ are three balloons ascending with velocities $U, 4U$ and $8U$ respectively. If stones of the same mass are dropped from each when they are at the same height $h$,which stone reaches the ground first?

$A$ ball is thrown vertically upwards from the ground $G$ with a speed $u$. It reaches a point $B$ at a height $h$ (lower than the maximum height) after time $t_1$. It returns to the ground after time $t_2$ from the instant it was at $B$ during the upward journey. Then $t_1t_2$ is equal to

If a ball is thrown vertically upwards with speed $u$,the distance covered during the last $t$ seconds of its ascent is

When a ruler falls vertically, $5$ different persons catch it with different reaction times. $(g = 9.8 \text{ ms}^{-2})$
$A$. Person $A$ has reaction time of $0.20 \text{ s}$
$B$. Person $B$ has reaction time of $0.22 \text{ s}$
$C$. Person $C$ has reaction time of $0.18 \text{ s}$
$D$. Person $D$ has reaction time of $0.19 \text{ s}$
$E$. Person $E$ has reaction time of $0.21 \text{ s}$
What is the correct order of the distance travelled by the ruler for each person?

$A$ player throws a ball upwards with an initial speed of $29.4 \; m s^{-1}$. What is the direction of acceleration during the upward motion of the ball?