A particle starts its motion from rest under the action of a constant force. If the distance covered in first $10$ seconds is $S_1$ and that covered in the first $20$ seconds is $S_2$ , then

A bus moving along a straight highway with speed of $72 \mathrm{~km} / \mathrm{h}$ is brought to halt within $4 \mathrm{~s}$ after applying the brakes. The distance travelled by the bus during this time (Assume the retardation is uniform) is__________.$\mathrm{m}$.

A man is at a distance of $6\,m$ from a bus. The bus begins to move with a constant acceleration of $3\,ms ^{-2}$. In order to catch the bus, the minimum speed with which the man should run towards the bus is $.........ms ^{-1}$

A small electric car has a maximum constant acceleration of $1\,m / s ^2$, a maximum constant deceleration of $2\,m / s ^2$ and a maximum speed of $20\,m / s$. The amount of time it would take to drive this car $1\,km$ starting from rest and finishing at rest is $.........\,s$

A body starting from rest moves with constant acceleration. The ratio of distance covered by the body during the $5^{th}$ sec to that covered in $5\, sec$ is