Rankers Physics
Topic: Kinematics
Subtopic: Relative Motion in Two Dimension

A bird is flying towards south with a velocity 40km/h and a train is moving with a velocity 40 km/h towards east. What is the velocity of the bird w.r.t. an observer in the train ?
40 √2 km/h. N-E
40 √2 km/h. S-E
40 √2 km/h. S-W
40 √2 km/h. N-W

Solution:

The relative velocity of the bird with respect to the observer in the train is found by combining the bird's velocity (south) and the train's velocity (east) using the Pythagorean theorem.

\[
v_{\text{relative}} = \sqrt{(40^2 + 40^2)} = \sqrt{3200} = 40\sqrt{2} \, \text{km/h}
\]

The direction is \( 45^\circ \) south of west.

Thus, the relative velocity is:

\[ {40\sqrt{2} \, \text{km/h} \text{ at } 45^\circ \text{ south of west}}
\]

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