Two trains, which are moving along different tracks in opposite directions, 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 m apart. Graphs given in figure show their velocities as function of time as the trains slow down. The separation between the trains when both have stopped is

Options

A. `120m`
B. 280 m
C. 60 m
D. 20 m

Answer

D

Explanation

d. Initial distance between trains is 300m. Displacement of trains
can be calculated by area under `V-t graph`.

Displacement of train `1 = 1/2 xx 10xx 40 = 200m`
Displacement of train `2 = 1/2 xx 8 xx (-20) = -80m`
which means it moves towards left.
Hence, distance between the two is `300 - 200 - 80 = 20m`.