A weight of mass m is fixed to the middle point of a string of length l and rotates about an axis joining the ends of the string. The system is in contact with its environment at temperature T. Calculate the tension R between the ends of the string in terms of its dependence upon distance x between the ends and the temperature. My thoughts: clearly, the x-components of the tension will cancel and we are left with the y-components of the tension which provides the centripital force. The energy of the rotating mass is given by 1/2 I w^2 (where w is the angular frequency). Since the string is in thermal equilibrium with the envrionment we can equate it with the average thermal energy for 1 degree of freedom: 1/2 kT What I don't understand, is how to go from the energy to the tension on the string.