Question
A train of $$150\,m$$ length is going towards north direction at a speed of $$10\,m{s^{ - 1}}.$$ A parrot flies at a speed of $$5\,m{s^{ - 1}}$$ towards south direction parallel to the railway track. The time taken by the parrot to cross the train is equal to
A.
$$12\,s$$
B.
$$8\,s$$
C.
$$15\,s$$
D.
$$10\,s$$
Answer :
$$10\,s$$
Solution :
So by figure the velocity of parrot w.r.t. train is $$ = 5 - \left( { - 10} \right) = 15\,m/\sec $$
so time taken to cross the train is $$ = \frac{{{\text{length of train}}}}{{{\text{relative velocity}}}} = \frac{{150}}{{15}} = 10\,\sec $$
So by figure the velocity of parrot w.r.t. train is $$ = 5 - \left( { - 10} \right) = 15\,m/\sec $$
so time taken to cross the train is $$ = \frac{{{\text{length of train}}}}{{{\text{relative velocity}}}} = \frac{{150}}{{15}} = 10\,\sec $$
