Question

A string under a tension of 43.0 N is used to whirl a rock in a horizontal circle of radius 2.45 m at a speed of 20.9 m/s on a frictionless surface as shown in the figure below. As the string is pulled in, the speed of the rock increases. When the string is 1.00 m long and the speed of the rock is 49.0 m/s, the string breaks. What is the breaking strength, in newtons, of the string?

Answer 1

tension=mv^2/r initial. figure mass.

now, final tension
tensionbreaking= m v^2/r you know mass, v, and r.