A body starts with an initial velocity of $10\,ms ^{-1}$ and is moving along a straight line with constant acceleration. When the velocity of the particle is $50\,ms ^{-1}$, the acceleration is reversed in direction. The velocity of the particle when it again reaches the starting point is $............\,m/s^{-1}$

Two stones are thrown up simultaneously with initial speeds of ' $u_1$ and $u_2\left(u_2 > u_1\right)$. They hit the ground after $6\,s$ and $10\,s$ respectively. Which graph in figure correctly represents the time variation of $\Delta x=\left(x_2-x_1\right)$, the relative position of the second stone with respect to the first upto $t=10\,s$ ? Assume that the stones do not rebound after hitting the ground.

A body $A$ moves with a uniform acceleration $a$ and zero initial velocity. Another body $B$, starts from the same point moves in the same direction with a constant velocity $v$. The two bodies meet after a time $t$. The value of $t$ is

A car is moving with speed of $150\,km / h$ and after applying the brake it will move $27\,m$ before it stops. If the same car is moving with a speed of one third the reported speed then it will stop after travelling $....m$ distance.