$A$ bus is moving with a velocity $10\, ms^{-1}$ on a straight road. $A$ scooterist wishes to overtake the bus in $100\, s$. If the bus is at a distance of $1\, km$ from the scooterist,with what velocity should the scooterist chase the bus? ......... $ms^{-1}$

$A$ student is standing at a distance of $50 \, m$ from the bus. As soon as the bus begins its motion with an acceleration of $1 \, m/s^2$,the student starts running towards the bus with a uniform velocity $u$. Assuming the motion to be along a straight road,the minimum value of $u$,so that the student is able to catch the bus is.........$m/s$.

$A$ $210 \ m$ long train is moving due North at a speed of $25 \ m/s$. $A$ small bird is flying due South a little above the train with a speed of $5 \ m/s$. The time taken by the bird to cross the train is $........ \ s$.

What are the speeds of two objects if,when they move uniformly towards each other,they get $4\,m$ closer in each second and when they move uniformly in the same direction with the original speeds,they get $4.0\,m$ closer each $10\,s$?

At a metro station, a girl walks up a stationary escalator in $20 \,s$. If she remains stationary on the escalator, then the escalator takes her up in $30 \,s$. The time taken by her to walk up on the moving escalator will be (in $\,s$)

Two trains $A$ and $B$ of length $400 \; m$ each are moving on two parallel tracks with a uniform speed of $72 \; km \; h^{-1}$ in the same direction,with $A$ ahead of $B$. The driver of $B$ decides to overtake $A$ and accelerates by $1 \; m \; s^{-2}$. If after $50 \; s$,the guard of $B$ just brushes past the driver of $A$,what was the original distance (in $m$) between them?