$A$ parachutist drops freely from an aeroplane for $10\,s$ before the parachute opens. Then he descends with a net retardation of $2.5\,m/s^2$. If he bails out of the plane at a height of $2495\,m$ and $g = 10\,m/s^2$,his velocity on reaching the ground will be .......$m/s$.

What is reaction time? On what does the reaction time depend?

$A$ particle starts from rest,accelerates at $2 \, m/s^2$ for $10 \, s$,then moves at a constant speed for $30 \, s$,and finally decelerates at $4 \, m/s^2$ until it stops. What is the total distance travelled by it in $m$?

$A$ monkey climbs up a slippery pole for $3 \ s$ and subsequently slips for $3 \ s$. Its velocity at time $t$ is given by $v(t) = 2t(3 - t)$ for $0 < t < 3$ and $v(t) = -(t - 3)(6 - t)$ for $3 < t < 6$ in $m/s$. It repeats this cycle until it reaches the height of $20 \ m$.
$(a)$ At what time is its velocity maximum?
$(b)$ At what time is its average velocity maximum?
$(c)$ At what time is its acceleration maximum in magnitude?
$(d)$ How many cycles (counting fractions) are required to reach the top?

Two trains '$A$' and '$B$' of length '$l$' and '$4l$' are travelling into a tunnel of length '$L$' on parallel tracks from opposite directions with velocities $108\,km/h$ and $72\,km/h$,respectively. If train '$A$' takes $35\,s$ less time than train '$B$' to cross the tunnel,then the length '$L$' of the tunnel is $...........\,m$. (Given $L = 60l$)

The speed-time graph for a body moving along a straight line is shown in the figure. The average acceleration of the body may be .......... $m/s^2$.