22A
YOUR ANSWER: 93.25 percent.
You are correct.
Now, let's see how we could solve for the input power, if the efficiency and output were
known.
First, we will use the correct formula:
Efficiency = output x 100.
input
Now, suppose that we had a 5-horsepower motor operating at 74.6 per cent efficiency.
a. Put into formula known values:
74.6 = 5 x 746 x 100.
input
b. Multiply both sides of the equation by "input":
Input x 74.6 = 5 x 746 x 100 x input
input
c. Then, we have
input x 74.6 = 3730 x 100 = 373,000
input = 373,000 = 5,000 watts.
74.6
Now, you solve one.
A 4-horsepower motor operates at 80 percent efficiency; what is the input power?
3730 watts.
frame 26A
373 watts.
frame 21A
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IT0348
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