When traveling at top speed, a roller coaster train with a mass of 12,000 kg has a velocity of 30 m/s. The kinetic energy of the train at top speed is[___]J.

Kinetic energy is calculated with KE = ½mv². Substituting the train’s mass and speed gives KE = ½ × 12,000 × 30² = 6,000 × 900 = 5,400,000 J. The correct choice is 5,400,000 J.

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