Question

A bird flies to and fro between two cars which move with velocities $v_1$ and $v_2$. If the speed of the bird is $v_3$ and the initial distance of separation between them is d, find the total distance covered by the bird till the cars meet.

Answer 1

$v_{12}=v_1+v_2$

Time taken to cover distance d

$t=\frac{d}{v_{12}}=\frac{d}{v_1+v_2}$

Since the speed of bird is $v_3$, therefore, distance covered by bird in time t

$v_3\times t=\frac{d}{v_1+v_2}{v}_3$