Two bodies A and B are 10 km apart such that B is to the south of A. A and B start moving with the same speed 20 km/hr eastward and northward respectively then find. N

(a) relative velocity of A w.r.t. B. W/ E
(b) minimum separation attained during motion
(c) time elapsed from starting, to attain minimum separation.

A body is projected with velocity $u_1$ from point $A$ as shown in the figure. At the same time, another body is projected vertically upwards with a velocity $u_2$ from point $B$. What should be the value of $\frac{u_1}{u_2}$ for both bodies to collide?

A child runs to and fro with a speed $9 \mathrm{km} {\mathrm{h}}^{-1}$ (with respect to the belt) on a long horizontally moving belt (figure) between $h$ is father and mother located $50 \mathrm{m}$ apart on the moving belt. The belt moves with a speed of $4 \mathrm{km} {\mathrm{h}}^{-1}$. For an observer on the stationary platform outside, what is the $\left(a\right)$ speed of the child running in the direction of motion of the belt and $\left(b\right)$ speed of the child running opposite to the direction of motion of the belt? $\left(c\right)$ time taken by the child in $\left(a\right)$ and $\left(b\right)$. Which of the answers will alter if motion is viewed by one of the parents?