A train `100 m` long travelling at `40 ms^(-1)` starts overtaking another train `200 m` long travelling at `30 ms^(-1)`. The time taken by the forst train to pass the second train comletely is .

Options

A. ` 30s`
B. ` 40 s`
C. ` 50 s`
D. ` 60 s`

Answer

A

Explanation

Relative velocity of overtaking=`40-30=10 ms^(-1)`. Total relative distance coverd with this relative velocity during overtading=`100+200=300 m`
So time taken `=3000//300 m`
So time taken `=3000//10=30 s`.