Question

A bird is tossing (flying to and fro) between two cars moving towards each other on a straight road. One car has a speed of 18 m/h while the other has the speed of 27 km/h. The bird starts moving from first car towards the other and is moving with the speed of 36 km/h and when the two cars were separated by 36 km. What is the total distance covered by the bird ? What is the total displacement of the bird ?

Answer 1

According to the problem, Speed of first car =$18km/h$

Speed of second car $=27km/h$

$\therefore$ Relative speed of each car w.r.t each other

$=18+27=45km/h$

Distance between the cars$=36km$

$\therefore$ Time of meeting the cars (t)

$=\frac{Distancebetweenthecars}{Relativespeedofcars}$

$=\frac{36}{45}=\frac{4}{5}h=0.8h$

Speed of the bird $\left(v_b\right)=36km/h$

Distance covered by the bird

$=v_b\times t=36\times 0.8=28.8km$

Concept of relative velocity (for 1-D): If two objects are moving along the same straight line and we are observing the motion from the frame of one object. Then for the relative velocity, it will be subtracted for velocities in same direction and added for velocities in opposite directions. (Remember: add or subtract them with proper sign conventions).

Concept of relative velocity (for 1-D): If two objects are moving along the same straight line and we are observing the motion from the frame of one object. Then for the relative velocity, it will be subtracted for velocities in same direction and added for velocities in opposite directions. (Remember: add or subtract them with proper sign conventions).