Question

A mass attached to once end of a string crosses top-most point on a vertical circle with critical speed. Its centripetal acceleration when string becomes horizontal will be (g = gravitational acceleration)

• A. g
• B. $3g$
• C. $4g$
• D. $6g$

Answer 1

The correct option is B $3g$

The speed when a string is horizontal, $v=\sqrt{3gr}$

Hence, centripetal acceleration, $a_r=\frac{v^2}{r}=3g$

Hence, the answer is option-(B).