1. A machine is supplied energy at a rate of 4,000 W and does useful work at a rate of 3,760 W. What's the efficiency of the machine?
A. 92 percent
B. 94 percent
C. 97 percent
D. 96 percent
Actual Efficiency/ Theoretical Efficiency *100% = efficiency %
3760 W / 4000 W * 100% = 94%
To find the efficiency of a machine, you need to divide the useful work output by the energy input and then multiply by 100 to obtain a percentage. Here's how you can calculate it:
Step 1: Identify the given values
Energy input (P_in) = 4,000 W
Useful work output (P_out) = 3,760 W
Step 2: Use the formula to calculate efficiency (η)
η = (P_out / P_in) * 100
Step 3: Substitute the values into the formula and calculate
η = (3,760 / 4,000) * 100
η ≈ 94
Step 4: Determine the given options that are closest to the calculated efficiency
Comparing the calculated efficiency of approximately 94 to the given options, we can see that option B, 94 percent, is the closest answer.
Therefore, the answer is B. 94 percent.