Question

A string can withstand a force of 120 N before breaking. A 3.0 kg mass is tied to the string and whirled in a horizontal circle with a radius of 1.50 m. What is the maximum speed that the mass can be whirled at before the string breaks?

Answer 1

Centripetal force is provided by the string: F = m v^2 / r. Solve for v:

v = sqrt(F r / m) = sqrt(120 N * 1.50 m / 3.0 kg) = sqrt(60) ≈ 7.75 m/s.

So the maximum speed is about 7.75 m/s.