# Physics

posted by Ashton

A light–rail commuter train draws 635 A of 640–V DC electricity when accelerating. What is its power consumption rate in kilowatts?
(in kW) 406 kW
You are correct.

How long does it take to reach 30.0 m/s starting from rest if its loaded mass is 4.90×104 kg, assuming 93.0% efficiency and constant power?
(in s) 58.3 s
You are correct.

Find its average acceleration.
(in m/s^2) 0.514 m/s^2
You are correct.

What is the ratio of the acceleration you found for the light–rail train compares to what might be typical for an automobile? (A typical automobile can accelerate from 0 to 60 mph in 10 s.)

Need help with the last question please! I found the automobiles acceleration to be 2.778 and I divided that by the acceleration i found for the train:
2.778/.514=5.40 but it isn't the right answer. What am I doing wrong?

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