Question Detail
Question
An object is revolving in a horizontal circle at the end of a string. If the speed of the object is tripled, and the string length is also tripled, by what factor does the tension in the string change?
Correct Answer
Option B is the correct answer.
Detailed Explanation
Tension provides centripetal force: T = mv²/r. Let new v' = 3v and new r' = 3r. Then T' = m(3v)²/(3r) = m(9v²)/(3r) = 3(mv²/r) = 3T.
Hint
Write the formula for the new tension in terms of the old speed and radius. Remember to square the new speed.