Question

A 1 kg stone at the end of 1 m long string is whirled in a vertical circle at constant speed of 4 m/sec. The tension in the string is 6 N, when the stone is at (g = 10 m/$se{c}^2$)

• A. Top of the circle
• B. Bottom of the circle
• C. Half way down
• D. None of the above

Answer 1

The correct option is A

Top of the circle

mg = 1$\times$10 = 10N, $\frac{m{v}^2}{r}$ = $\frac{1\times \left(4^2\right)}{1}$ = 16
Tension at the top of circle = $\frac{m{v}^2}{r}$ - mg = 6N
Tension at the bottom of circle = $\frac{m{v}^2}{r}$+mg = 26N