Question

 A sled with a mass of 25.0 kg rests on a horizontal sheet of essentially frictionless ice. It is attached by a 5.00-m rope to a post set in the ice. Once given a push, the sled revolves uniformly in a circle around the post. If the sled makes five complete revolutions every minute, find the force F exerted on it by the rope.

Answer 1

5 revolutions every minute is

$$f=5/60=0.083\text{ s}^{-1}.$$

The speed is

$$v=\frac{2\pi R}{T}=2\pi Rf=2.6\text{ m/s}.$$

The force is

$$F=ma=m\frac{v^2}{R}=33.8\text{ N}.$$