A string under a tension of 43 N is used to whirl a rock in a horizontal circle of radius 2.1 m at a speed of 15.89 m/s. The string is pulled in, and the speed of the rock increases. When the string is 0.948 m long and the speed of the rock is 59 m/s, the string breaks.

Question

A string under a tension of 43 N is used to whirl a rock in a horizontal circle of radius 2.1 m at a speed of 15.89 m/s. The string is pulled in, and the speed of the rock increases. When the string is 0.948 m long and the speed of the rock is 59 m/s, the string breaks.
What is the breaking strength of the string? Answer in units of N.

Scott · Answer

f = m v^2 / r f = 43 N * (59/15.89)^2 / (.948/2.1)