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/sec²)

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

Answer 1

Answer: (A)

Top of the circle

Answer 2

$mg = 1 \times 10 = 10N,$ $\frac{mv^{2}}{r} = \frac{1 \times (4)^{2}}{1} = 16$

Tension at the top of circle = $\frac{mv^{2}}{r} - mg = 6N$

Tension at the bottom of circle = $\frac{mv^{2}}{r} + mg = 26N$