Q. A stone is tied to one end of a string $50\ cm$ long is whirled in a horizontal circle with a constant speed. If the stone makes 10 revolutions in $20\ s$, what is the magnitude of acceleration of the stone
A) $493\ cm/s^{2}$
B) $720\ cm/s^{2}$
C) $860\ cm/s^{2}$
D) $990\ cm/s^{2}$
Explanation
(a) $a = 4\pi^{2}n^{2}r = 4\pi^{2}\left( \frac{1}{2} \right)^{2} \times 50 = 493\ cm/s^{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.