A machine gun is attached to a railroad flatcar that rolls with negligible friction.If the railroad car has a mass of 6.25 ´ 10⁴ kg,how many bullets of mass 25 g would have to be fired at 250 m/s off the back to give the railroad car a forward velocity of 0.5 m/s? A)400 B)2 000 C)3 000 D)5 000

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Quizplus · Accepted Answer

The momentum gained by the railroad car must equal the momentum lost by the bullets. Using the formula: (mass of bullets * velocity of bullets) = (mass of car * velocity of car), we find that 5,000 bullets are needed.

A Machine Gun Is Attached to a Railroad Flatcar That