Question

A particle of mass m is tied to a light string of length l and rotated along a vertical circular path. What should be the minimum speed at the highest point of its path so that the string does not become slack at any position?

• A. $\sqrt{2gl}$
• B. $\sqrt{gl}$
• C. zero
• D. $\sqrt{gl/2}$

Answer 1

Answer: (B)

$\sqrt{gl}$

Answer 2

For v₁ to be minimum, T₁ = 0.

or v₁ = $\sqrt{gl}$.