It’s a hot day. You buy four fans and plug them into outlets. The outlets are powered by a circuit protected by a 20 A circuit breaker. If each fan is rated at 250 W and the outlet voltage is 120 V. Will the circuit breaker interrupt current fl ow?
What will be an ideal response?
P = VI, therefore I = P/V; I = 250 W/120 V = 2.08 A per fan. 2.08 A X 4 =8.33 A. Since 20 A > 8.33 A, the circuit breaker will not trip.
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A line-sensing control uses a mechanical thermostat or electrical controller to measure the _____.
a. actual pipe temperature b. ambient temperature surrounding the pipe c. estimated pipe temperature d. heat levels surrounding the pipe
Kleen Corp., a privately owned and operated single-stream recycling facility, has annual contracts with several cities in the Tri-County Metropolitan Area. Kleen Corp. wants to add a new set of sensors to its existing machinery that will separate plastics and metals from paper and glass materials earlier in the separation process. Two versions of the sensor equipment are available from the Green Corporation. Model 400 has a first cost of $700,000, while Model 1000 costs $1 million. Both have an expected 10% salvage value after their respective useful lives of 6 and 3 years. Assume you work for Kleen Corp. as a project engineer. You have made first-cut estimates of the annual savings (with no annual increases for efficiency) and expenses (AOC with no annual decreases or
increases) for both models.
(a) Perform an ROR analysis using MARR = 5% per year to recommend one of the two models to your president. You know that your president likes dollar-per-year figures, and will want to see a plot of the annual worth amounts for different rate of return values when you visit with her.
(b) Before you finalize your recommendation, ensure that there is no ranking inconsistency present with these two alternatives. If there is not, no problem. If there is, be prepared to provide the logic of your recommendation.
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The purpose of the miniature ON/OFF switches on a breakout box is to
a. measure the individual interface signals. b. change the voltage of individual interface signals. c. allow the cross-patching of the individual interface conductors. d. allow the interruption of the individual interface conductors for isolated testing.
Calculate the speed of sound for the U.S. standard atmosphere using, c ? kRT where c represents the speed of sound in m/s, k is the specific heat ratio for air (k = 1.4), and R is the gas constant for the air (R = 286.9 J/kg·K) and T represents the temperature of the air in Kelvin. The speed of sound in atmosphere is the speed at which sound propagates through the air. You may use Excel to solve this problem.
