Physics Two Dimensional Motion Question 67
Question: A bird is flying towards north with a velocity $ 40km,{{h}^{-1}} $ and a train is moving with velocity $ 40km,{{h}^{-1}} $ towards east. What is the velocity of the bird noted by a man in the train?
Options:
A)$ 40\sqrt{2},km,{{h}^{-1}},N-E $ B)$ 40\sqrt{2},km,{{h}^{-1}},S-E $ C)$ 40\sqrt{2},km,{{h}^{-1}},N-W $ D)$ 40\sqrt{2},km,{{h}^{-1}},S-W $
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Answer:
Correct Answer: C
Solution:
[c] To find the relative velocity of bird w.r.t train, superimpose velocity $ -\vec{v}T $ on both the objects. Now as a result of it , the train is at rest, while the bird possesses two velocities, $ \vec{v} $ B towards north and $ -{{\overrightarrow{v}} _{T}} $ along west. $ | \vec{v}BT |=\sqrt{{{| \vec{v}B |}^{2}}+{{| -\vec{v}T |}^{2}}} $ [By formula, $ \theta =90{}^\circ $ ] $ =\sqrt{40^{2}+40^{2}}=40\sqrt{2} $
$ km{{h}^{-1}} $ north-west
BETA
