Two trains, which are moving along different tracks in opposite directions towards each other, are put on the same track due to a mistake. Their drivers, on noticing the mistake, start slowing down the trains when the trains are $300 \mathrm{m}$ apart. Graphs given below show their velocities as a function of time as the trains slow down. What is the separation between the trains (in metre) when both have stopped?

  

A lift starts from rest. Its acceleration is plotted against time in the following graph. When it comes to rest, its height above its starting point is

Two balls are projected from points $A$ and $B$ in a vertical plane as shown in the figure. $AB$ is a straight vertical line. The balls will collide in mid-air if  $\frac{V_1}{V_2}$ is equal to, 

In the given figure $AB$ is a pipe fixed to the ground at an inclination of $37°.$ A ball is projected from point $O$ at a speed of $u=20 \mathrm{m}/\mathrm{s}$ at angle of $53°$ to the horizontal and it smoothly enter the pipe with its velocity parallel to the axis of the pipe. Then length of pipe (in metre) is: (Take $g=10{ ms}^{-2}$) (Approximate the answer to the nearest integer.)