A point mass m is moved in a vertical circle of the radius r with the help of a string. The velocity of the mass is 7gr at the lowest point. The tension in the string at the lowest point is:

Question

Quantrex Academy · Accepted Answer

Correct answer: C. 8mg

First, make the free body diagram when a mass bob is attached with a string of length, $r$ rotating in a vertical circle.

A point mass m is moved in a vertical circle of the radius r with the help of a string. The velocity of the mass is 7gr

Given, $v = \sqrt{7gr}$ , now make the equation between centripetal force and surface tension which are acted in opposite direction,

$⇒ T - mg = \dfrac{m ( \sqrt{7gr}{)}^{2}}{r}$ $⇒ T = 8mg$ .

A point mass m is moved in a vertical circle of the radius r with...

Options

Correct answer

Step-by-step solution

More from Laws of Motion