Question:
A bob is whirled in a horizontal circle by means of a string at an initial speed of 10 rpm. If the tension in the string is quadrupled while keeping the radius constant, the new speed is:
A bob is whirled in a horizontal circle by means of a string at an initial speed of 10 rpm. If the tension in the string is quadrupled while keeping the radius constant, the new speed is:
Updated On: Dec 16, 2025
- 20 rpm
- 40 rpm
- 5 rpm
- 10 rpm
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The Correct Option is A
Solution and Explanation
Tension (T) provides the centripetal force: T = mv2/r. With r and m constant, T ∝ v2. If
T2 = 4T1, then v22 = 4v12.
Given v1 = 10 rpm, then v2 = √4 × 102 = 20 rpm.
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