As an automotive engineer, you’re charged with improving the fuel economy of your company’s vehicles. You realize that the rotational kinetic energy of a car’s wheels is a significant factor in fuel consumption, and you set out to lower it. For a typical car, the wheels’ rotational energy is 40% of their translational kinetic energy. You propose a redesigned wheel with the same radius but 10% lower rotational inertia and 20% less mass. What do you report for the decrease in the wheel’s total kinetic energy at a given speed?
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