A yo-yo of total mass m consists of two solid cylinders of radius R, connected by a small spindle of negligible mass and radius r. The top of the string is held motionless while the string unrolls from the spindle. Show that the acceleration of the yo-yo is g/(1 + R2/2r2). [Hint: The acceleration and the tension in the string are unknown. Use τ = ΔL/Δt and F = ma to determine these two unknowns.]