Answer to Question #150697 in Physics for Sean Crowly

Question

A student can’t really use a yo-yo very well, so he swings it around his head in a horizontal circle. He notices that the faster he swings it, the more tension there is in the string. He wonders if there is a relationship between the tension in the string and the period of the swings. He hypothesizes that tension increases with decreasing period. Using your knowledge of physics, make a statement that supports his hypothesis. Explain, but do not use an equation.

Answer 1

Yes, student's hypothesis is right. Tension increases with speed squared. Period is length of the trajectory divided by speed. So, tension increases because speed increases > period decreases because speed increases. Since both statements have 'because speed increases', we can freely say that tension increases because period decreases.