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Physics · MOTION IN A PLANE
हिन्दीA motorboat is racing towards north at \( 25\text{ km/h} \) and the water current in that region is \( 10\text{ km/h} \) in the direction of \( 60^\circ \) east of south as shown in the vector diagram. The direction angle \( \phi \) of the resultant velocity vector relative to the north direction is approximately:
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Correct answer · Option B
23.4°
Explanation
The angle between north (\( \vec{v}_b \)) and current (\( \vec{v}_c \)) is \( \theta = 180^\circ - 60^\circ = 120^\circ \). Using law of sines, \( \frac{R}{\sin 120^\circ} = \frac{v_c}{\sin \phi} \implies \sin\phi = \frac{10 \sin 120^\circ}{21.8} \approx 0.397 \implies \phi \approx 23.4^\circ \).
