Question

A train of $150$ length is going toward north direction at a speed of $10m{s}^{-1}$. A parrot flies at a speed of $5m{s}^{-1}$ towards south direction parallel to the railway track. The time taken by the parrot to cross the train is equal to

• A. $12s$
• B. $8s$
• C. $15s$
• D. $10s$

Answer 1

The correct option is D $10s$

Relative velocity of the parrot w.r.t. the train $[10-(-5\left)\right]=(10-(-5\left)\right)m/s=15m/s$
Time taken by the parrot to cross the train
$=\frac{150}{15}=10$s.