In order to increase the kinetic energy of a speeding train by 44%, 42MJ of work must be performed (1 MJ = 106 J). If the final velocity of the train (after the 42 MJ of work) is 9 m/s, what is the mass of the train in metric tons (1 metric ton = 1000 kg) ?

Question

Physics

Diana Merritt

27 July, 22:11

In order to increase the kinetic energy of a speeding train by 44%, 42MJ of work must be performed (1 MJ = 106 J). If the final velocity of the train (after the 42 MJ of work) is 9 m/s, what is the mass of the train in metric tons (1 metric ton = 1000 kg) ?

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Orion Weber · Answer 1

100 % increase makes an amount 2 times.

44 % increase = 42 MJ

100 % increase = 95.45 MJ

final kinetic energy = 2 x 95.45 MJ

= 190.9 x 10⁶ J

1/2 m v² = 190.9 x 10⁶

.5 x m x 9² = 190.9 x 10⁶

m = 4.71 x 10⁶ kg

= 4710 metric ton.