An aero plane is flying vertically upwards with a uniform speed of $500 \mathrm{m} {\mathrm{s}}^{-1}$. When it is at the height of $1000 \mathrm{m}$ above the ground, a shot is fired at it with a speed of $700 \mathrm{m} {\mathrm{s}}^{-1}$ from a point directly below it. The minimum uniform acceleration of the aero plane now so that it may escape from being hit?  $\left(g=10 \mathrm{m} {\mathrm{s}}^{-2}\right)$

Shown in the figure, is the position-time graph for two children, going home from school. Which of the following statements about their relative motion is true, after both of them started moving? (Consider $1-D$ motion). Their relative velocity

The figure shown below represents the velocity-time graphs of the two particles $P_1$ and $P_2$ moving along a straight line. The magnitude of their relative velocity