Q43 / 72 · NTA Abhyas (JEE Main) 2020 · Physics · Motion In Two Dimensions

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 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?

Figure   Figure

Correct answer: 20

Solution

Using the concept that the area under the v-t graph gives the change in displacement.

s1=12×10×40=200 m

s2=-12×8×20=-80 m

Relative displacement

s relative =s1-s2=200--80=280

Final separation=300-280=20 m

Hence, the correct answer is 20.

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