I whirl a mass m attached to a wire with length L and diameter d around my head in the horizontal plane. The mass takes t seconds to move around a circle. How far do the atoms in the wire move apart, compared to their spacing at rest? Young's modulus is given. Okay, so Y = stress/strain. For strain I need the force on the wire, and from there I can solve for the extension of the wire and use that to calculate how far the atoms move. But how do I get the force?