1. The problem statement, all variables and given/known data A particle of mass m is whirled on the end of a string of length R. The motion is in vertical plane in Earth's gravitational field . The instantaneous speed is v when the string makes angle Ө with the horizontal. Find the tension T in the string and the tangential acceleration at this instant. 2. Relevant equations 3. The attempt at a solution This is my classical mechanics homework problem. T= Fc+W sin theta . I have come up with this equation , is this correct . And how to find the tangential acceleration?