Q3-LR-1

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Pennsylvania State University *

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102

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Mechanical Engineering

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Jan 9, 2024

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1/23/23, 9:39 PM Lesson 3 - Quiz: EGEE 102 (SP23): Energy Conservation for Environmental Protection https://psu.instructure.com/courses/2224925/quizzes/4674334 1/8 Lesson 3 - Quiz Due Jan 28 at 11:59pm Points 25 Questions 13 Available Jan 23 at 12am - Jan 28 at 11:59pm Time Limit 20 Minutes Allowed Attempts 2 Instructions Attempt History Attempt Time Score LATEST Attempt 1 10 minutes 22 out of 25 Correct answers will be available on Jan 30 at 12am. Score for this attempt: 22 out of 25 Submitted Jan 23 at 9:38pm This attempt took 10 minutes. Remember that once you start the quiz, you cannot stop the timer. If you leave the quiz, the timer keeps running. You must finish in 20 minutes. Feedback for this Quiz (along with your responses and the correct answers) will be made available after the deadline for this Quiz. Take the Quiz Again 1 / 1 pts Question 1 Which one of the following is true about energy conversion devices? Total Energy Input = Useful Energy Output + Energy Dissipated to the surroundings Total Energy Input = Useful Energy Output
1/23/23, 9:39 PM Lesson 3 - Quiz: EGEE 102 (SP23): Energy Conservation for Environmental Protection https://psu.instructure.com/courses/2224925/quizzes/4674334 2/8 Total Energy Input = Energy Dissipated to the surroundings Total Energy Input = Efficiency X Total Energy Output Total energy = useful energy + waste energy. Refer to section 3.2: Energy Conversion Devices. 1 / 1 pts Question 2 Which one of the following devices is least energy efficient? (1 point) Power plant Electric motor Light bulb Typically a power plant has an efficiency of 35%, and an electric motor an efficiency of 90%. An incandescent electric bulb has an efficiency of 5% and fluorescent light bulbs have an efficiency of about 20%. Refer to section 3.3: Typical Efficiencies of Day to Day Devices. 1 / 1 pts Question 3 What is the form of useful energy output in the case of a computer screen?
1/23/23, 9:39 PM Lesson 3 - Quiz: EGEE 102 (SP23): Energy Conservation for Environmental Protection https://psu.instructure.com/courses/2224925/quizzes/4674334 3/8 Radiation Mechanical Thermal or Heat Chemical A computer screen converts electrical energy into radiation (the pictures and text that we see on the computer screen). Refer to section 3.2: Energy Conversion Devices. 1 / 1 pts Question 4 What is the primary form of useful energy output in the case of a car? Mechanical Thermal or Heat Radiation Chemical A car converts chemical energy from the burning of fuel into mechanical energy (rotation of wheels). Refer to section 3.2: Energy Conversion Devices. 1 / 1 pts Question 5
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1/23/23, 9:39 PM Lesson 3 - Quiz: EGEE 102 (SP23): Energy Conservation for Environmental Protection https://psu.instructure.com/courses/2224925/quizzes/4674334 4/8 What is the form of useful energy output in the case of a TV? Radiation Mechanical Thermal or Heat Chemical A TV converts electrical energy into radiation (the pictures that we see). Refer to section 3.2: Energy Conversion Devices. 1 / 1 pts Question 6 Energy can be created when we burn fossil fuels. (1 point) True False First law of thermodynamics states that Energy output must be equal to the input. It cannot be created. 2 / 2 pts Question 7 A heat engine converts thermal energy into what type of energy?
1/23/23, 9:39 PM Lesson 3 - Quiz: EGEE 102 (SP23): Energy Conservation for Environmental Protection https://psu.instructure.com/courses/2224925/quizzes/4674334 5/8 Mechanical Thermal Chemical Electrical A heat engine is defined as a device that converts heat energy into mechanical energy. 2 / 2 pts Question 8 What is the most common by product of fossil fuel-based energy conversion processes? Light Heat Sound Motion Most energy conversion processes produce heat as a by product. Refer to section 3.2: Energy Conversion Devices. 3 / 3 pts Question 9
1/23/23, 9:39 PM Lesson 3 - Quiz: EGEE 102 (SP23): Energy Conservation for Environmental Protection https://psu.instructure.com/courses/2224925/quizzes/4674334 6/8 If the energy input of a system is 115 calories and its output is 51 calories, what is the efficiency of the system? (Answer units: %) 44.35 System Efficiency = (useful energy output) / (total energy input) * 100. Please refer to section: Efficiency of Energy Conversion Devices. 0 / 3 pts Question 10 Incorrect Incorrect The Carnot efficiency of the automobile engine is 57%, and the flame temperature is 558 , what is the exhaust temperature ( )? ? Answer to two decimal places, do not include unit symbols. 357.33 Use the Carnot efficiency formula and temperatures in Kelvin. 3 / 3 pts Question 11 The flame temperature in an automobile engine is 1,315 °F, and the exhaust is emitted at 257 °F. What is the Carnot efficiency of the engine? (Answer with units of %. i.e. 30 not 0.3. you do not need to provide the %) 59.62
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1/23/23, 9:39 PM Lesson 3 - Quiz: EGEE 102 (SP23): Energy Conservation for Environmental Protection https://psu.instructure.com/courses/2224925/quizzes/4674334 7/8 Use the Carnot efficiency formula and temperatures in Kelvin. Please refer to section covering The Carnot Efficiency. 3 / 3 pts Question 12 The useful output from a heat engine is 212 cal. The energy that is wasted is 4,235 J. What is the Carnot efficiency of the engine? (Answer with units of %. i.e. 30 not 0.3. you do not need to provide the %) 17.32 Efficiency = ((useful energy output) / (useful energy output + waste energy output))*100. Note: Use units consistently. Please refer the section of the Efficiency of Energy Conversion Devices. 3 / 3 pts Question 13 The following step efficiencies apply to the use of gasoline in a car: Crude production: 95.9%, Refining 80.5%, Transportation 93.4%, Engine efficiency 20%. What is the total efficiency of the process? (Answer units: %, i.e. input 10 not 0.1. Be sure to exclude the % as Canvas does not accept symbols) 14.42
1/23/23, 9:39 PM Lesson 3 - Quiz: EGEE 102 (SP23): Energy Conservation for Environmental Protection https://psu.instructure.com/courses/2224925/quizzes/4674334 8/8 Overall Efficiency of a system is the product of step efficiencies. Please refer to section 3.9: Calculating Overall Efficiency. Quiz Score: 22 out of 25