wheel A has mass m = 2 kg, radius R(A) = 1 m wheel B has mass m = 2 kg, radius R(B) = 2 mBoth wheels roll at the same angular speed: omega = 1.5 rad/s.
Which wheel has more rotational kinetic energy? Explain.
Answer: The rotational kinetic energy depends on moment of inertia and angular speed: rot KE = 0.5 * I * (omega)^2 The angular speed omega is the same for both wheels, but the moment of inertia is not. The moment of inertia depends on mass and radius: I = (something) * (mass) * (radius)^2 Therefore I(A) (something) * (2 kg) * (1 m)^2 1 ------ = -------------------------------- = ----- I(B) (something) * (2 kg) * (2 m)^2 4 So I(B) = 4 I(A). That means that B has 4 times as much rotational KE as A.
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