A body $A$ starts from rest with an acceleration $a_1$ . After $2\ seconds$ , another body $B$ starts from rest with an acceleration $a_2$ . If they travel equal distance in the $5th\ second$ , after the start of $A$ , then the ratio $a_1$ : $a_2$ is equal to

The velocity of a bullet is reduced from $200\,m/s$ to $100\,m/s $ while travelling through a wooden block of thickness $10\,cm$. The retardation, assuming it to be uniform, will be 

The position$(x)$ of a particle at any time$(t)$ is given by $x(t) = 4t^3 -3t^2 + 2$ The acceleration and velocity of the particle at any time $t = 2\, sec$ are respectively

A body starts from rest with an acceleration $a_{1},$ after two seconds another body $B$ starts from rest with an acceleration $a _{2}$. If they travel equal distance in fifth second, after the starts of $A$, the ratio $a _{1}: a _{2}$ will be equal to

If velocity of particle moving along $x-$ axis is given as $v = k\sqrt x $ . Then ($a$ is acceleration)

Draw $x \to t$ graph for zero acceleration.