(a) If the electric motor draws 9.10 kW as the car moves at a steady speed of 20

Question

(a) If the electric motor draws 9.10 kW as the car moves at a steady speed of 20.0 m/s, what is the current delivered to the motor?

(b) How far can the car travel before it is "out of juice"?

Part 1 of 5 - Conceptualize

We guess that a current on the order of 100 amperes is delivered to the motor. A practical electric car should be able to travel several hundred kilometers on a single charge.

Part 2 of 5 - Categorize

We will calculate the electrical input and the mechanical output of the motor to find the current and the distance the car can travel at a steady speed.

Part 3 of 5 - Analyze

(a) From the equation relating power, current and potential, P = IV, we have

Part 4 of 5 - Analyze

(b) From the equation relating power, energy, and time,

P = U/t,

we have

Part 5 of 5 - Analyze

So, on a single charge, the car can go a distance of

I = P V

=   × 103 W   V =  A.

Explanation / Answer

(a)P = V x i
9100=12 x i
i = 758.33amps (current flow)

Energy = P • t
2.20 x 107 = 9100 x t
t = 2417 X 58 sec

(b) d = v x t
d = 20 x 2417.58
d = 48351.64 m
d = 48.35 Km maximum range at 20 m/sec(distance)

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