Question

A bird was flying parallel to the ground in east-west direction with a constant speed at a height of 100 m from the ground. Sunita standing in the middle of the park, first observed the bird in the east at an angle of elevation of $30^\circ$. After 2 minutes, she observed the bird in the west from the same position making an angle of elevation of $45^\circ$. Find the speed of the bird. (Take $\sqrt{3} = 1.73$)

Accepted Answer

Let height $h = 100	ext{ m}$. Distance to east $d_1 = \frac{100}{	an 30^\circ} = 100\sqrt{3}	ext{ m}$. Distance to west $d_2 = \frac{100}{	an 45^\circ} = 100	ext{ m}$. Total distance = $100\sqrt{3} + 100 = 100(1.73 + 1) = 273	ext{ m}$. Time = 2 min = 120 s. Speed = $\frac{273}{120} = 2.275	ext{ m/s}$ (or $8.19	ext{ km/h}$).

Speed of flying bird

Explanation

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