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A mass of 2 kg is whirled in a horizontal circle by means of a string at an initial speed of 5 revolutions per minute. Keeping the radius constant, if we want the tension in the string to be doubled, then the new speed should nearly be

Options

  1. A2 . 25   rpm
  2. B7   rpm
  3. C10 rpm
  4. D14 rpm

Correct answer

B. 7   rpm

Step-by-step solution

F = m ω 2 r = mr 2 n π 2 thus F × n 2 n = resolution per second. thus 2 F F = n ′ n 2 or n ′ = 2 n = 5 2 rpm = 7 rpm

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