$A$ body starts from rest. What is the ratio of the distance travelled by the body during the $4^{th}$ and $3^{rd}$ second?

$A$ car moving with a velocity of $20 \,m \,s^{-1}$ is stopped in a distance of $40 \,m$. If the same car is travelling at double the velocity, the distance travelled by it for the same retardation is (in $\,m$)

$A$ body starting from rest at $t=0$ moves along a straight line with a constant acceleration. At $t=2 \ s$,the body reverses its direction keeping the acceleration same. The body returns to the initial position at $t=t_0$,then $t_0$ is

Tripling the speed of the motor car multiplies the distance needed for stopping it by

Two particles $A$ and $B$ start from rest and move for equal time on a straight line. Particle $A$ has an acceleration of $2\,m/s^2$ for the first half of the total time and $4\,m/s^2$ for the second half. The particle $B$ has acceleration $4\,m/s^2$ for the first half and $2\,m/s^2$ for the second half. Which particle has covered a larger distance?

The displacement of a particle starting from rest at $t=0$ is given by $s=9 t^2-2 t^3$. The time in seconds at which the particle will attain zero velocity is (in $s$)