Two balls $A$ and $B$ are thrown with the same velocity $u$ from the top of a tower. Ball $A$ is thrown vertically upwards and ball $B$ is thrown vertically downwards. If $t_A = 6 \ s$ and $t_B = 2 \ s$,then the velocity $u$ of each ball is ....... $m/s$.

$A$ ball is dropped from a high-rise platform at $t=0$ starting from rest. After $6$ seconds,another ball is thrown downwards from the same platform with a speed $v$. The two balls meet at $t=18\,s$. What is the value of $v$ in $m/s$? (Take $g= 10\,m/s^2$)

$A$ body is thrown vertically upwards with a velocity of $35 \ m/s$ from the ground. The ratio of the speeds of the body at times $3 \ s$ and $4 \ s$ of its motion is (Acceleration due to gravity $= 10 \ m/s^2$)

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?

$A$ ball is thrown vertically upwards from the top of a tower at $4.9 \ m/s$. It strikes the pond near the base of the tower after $3 \ s$. The height of the tower is........$m$

$A$ stone is dropped from the top of a tower of height $h = 60 \ m$. Simultaneously,another stone is projected vertically upwards from the foot of the tower. They meet at a height $\frac{2h}{3}$ from the ground level. Find the initial velocity of the stone projected upwards. (Take $g = 10 \ ms^{-2}$) (in $ms^{-1}$)