If a ball projected vertically upwards with a certain initial velocity from the ground crosses a point at a height of $25 \ m$ twice in a time interval of $4 \ s$,then the initial velocity of the ball is (Acceleration due to gravity $= 10 \ m \ s^{-2}$) (in $m \ s^{-1}$)

$A$ body dropped from the top of a tower clears $7/16$ of the total height of the tower in its last second of flight. The time taken by the body to reach the ground is........$s$

From the top of a tower,a ball is thrown vertically upward which reaches the ground in $6 \, s$. $A$ second ball thrown vertically downward from the same position with the same speed reaches the ground in $1.5 \, s$. $A$ third ball released from rest from the same location will reach the ground in ........ $s$.

$A$ body is projected vertically upwards with a velocity of $10\,m/s.$ It reaches the maximum vertical height $h$ in time $t.$ In $\frac{t}{2}$,the height covered is

If a body is thrown up with the velocity of $15 \, m/s$,then the maximum height attained by the body is .......... $m$ $(g = 10 \, m/s^2)$.

$Assertion$ : $A$ body can have acceleration even if its velocity is zero at a given instant of time.
$Reason$ : $A$ body is momentarily at rest when it reverses its direction.