Engineer Elizabeth likes the idea of hybrid cars, but doesn't like batteries. She decides to store energy with a flywheel: a flat circular disk of steel, with density ρ = 7800 kg/m3, diameter D = 1 m and height h.
Her car has a total mass of M = 1500 kg. Elizabeth plans on transferring kinetic energy from the car to the flywheel as the car slows down, then restoring it from the flywheel to get the car going after a stop. She comes up with a rough design: make the flywheel able provide the energy needed to accelerate the car from rest to v = 20 mph. The maximum angular velocity allowed by the car's frame is ω = 400 rpm.
Copyright © Michael Richmond.
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