Q. A body of mass $\sqrt{3}$ kg is suspended by a string from a rigid support. The body is pulled horizontally by a force $F$ until the string makes an angle of 30${^\circ}$ with the vertical. The value o $F$ and tension in the string are
A) 19.6 N; 19.6 N
B) 9.8 N; 9.8 N
C) 9.8 N, 19.6 N
D) 19.6 N, 9.8 N
Explanation
(d) $T\cos 30{^\circ} = mg$
or $T = \frac{mg}{\cos 30{^\circ}} = \frac{\sqrt{3} \times 9.8}{\sqrt{3}/2} = 19.6$N
$F = T\sin 30{^\circ} = 19.6 \times \frac{1}{2} = 9.8$N
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Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.