EGEE 101 MIDTERM EXAM 2

Which has more potential energy a). a cubic mile of water (a lake) behind a 300 ft tall dam b). a car moving at 120 mph across the Bonneville Salts Flats c). an oil tanker moving through the Suez Canal d). an atomic bomb in a silo in North Dakota - Correct Ans-A). B and C aren't stationary, and the height of D is 0. PE=mgh Which has more chemical energy?A.A cubic mile of water (a lake) behind a 300 ft tall dam B.A car moving at 120 mph across the Bonneville Salt Flats C.An oil tanker moving through the Suez Canal D.An atomic bomb in a silo in North Dakota - Correct Ans-Answer: C. A and B have no chemical energy. D has nuclear energy. C is a tanker full of oil, which is chemical Which has more nuclear energy?A.A cubic mile of water (a lake) behind a 300 ft tall dam B.A car moving at 120 mph across the Bonneville Salt Flats C.An oil tanker moving through the Suez Canal D.An atomic bomb in a silo in North Dakota - Correct Ans-Answer: D is the only option with any nuclear energy Which series goes from least energetic to most? A.X-rays, visible, ultraviolet, radio B.Radio, infrared, ultraviolet, X-rays C.Gamma, infrared, visible, microwave D.Microwave, ultraviolet, visible, radio - Correct Ans-Answer: B Refer to the graph from Lecture 2 What energy transformation occurs in the engine of the car? A. Chemical to potential B. Heat to mechanical C. Mechanical to heat D. Kinetic to potential - Correct Ans-B What energy transformation occurs in the brakes of the car? A. Chemical to potential B. Heat to mechanical EGEE 101 EGEE 101 C. Mechanical to heat D. Kinetic to potential - Correct Ans-C EGEE 101 Midterm Exam The inside of a concrete basement wall is 65° FThe outside is 55°F. Heat will leave the building through this wall via A.Convection B.Conduction C.Radiation D.None of the above/don't know - Correct Ans-Answer: B Conduction occurs through solid media...in this case, a concrete wall Which has higher power?• A: 1000 Joules used in 10 seconds• B: 1000 Joules used in 100 seconds• C: 1000 Joules used in 1000 seconds - Correct Ans-Answer: A1000J/10s = 100 WB = 10 WC = 1 W Which has higher energy?• A: 1000 Joules used in 10 seconds• B: 1000 Joules used in 100 seconds• C: 1000 Joules used in 1000 seconds• D: They all have the same energy - Correct Ans-Answer: D. Each option has 1000 Joules of energy A power plant consumes 1000 MJ of energy to produce 350 MJ of electric energy. What is the efficiency of this process? •A: 130%•B: 142%•C: 35%•D: 30%•E: 10% - Correct Ans-Answer: C. 350MJ/1000MJ A power plant produces 100 MJ of electricity and 300 MJ of wasted Heat. What is the Efficiency? •A: 20%•B: 25%•C: 80%•D: 400%•E: 33% - Correct Ans-Answer: BTotal energy = electricity + wasted heat = 100 MJ + 300 MJ = 400 MJ Efficiency = useful energy/total energy = 100 MJ of electricity / 400 MJ = 0.25 A power plant consumes 100 MJ of Energy, of which only 24 MJ are wasted heat. What is the efficiency?•A: 0.76•B: 0.24•C: 0.076•D: 1.00•E: 1.24 - Correct Ans-Answer: A). Useful energy = Total energy - Wasted energy = 100 MJ - 24 MJ = 76 MJ Efficiency = useful energy/total energy = 76 MJ / 100 MJ = 0.76 A power plant converts 100 kJ of coal into 70 kJ of electrical energy. EGEE 101 EGEE 101 What is the efficiency?•A: 30%•B: 70%•C: 130%•D: 142%•E: 10% - Correct Ans Answer: B70 kJ / 100 kJ Your home converts 70 kJ of electrical energy into 35 kJ of useful energy (heat, electric) and 35 kJ of wasted energy. What is your home's efficiency?•A: 35%•B: 200%•C: 75%•D: 50%•E: 70% - Correct Ans-Answer: DTotal energy = 35 kJ + 35 kJ = 70 kJ Efficiency = 35 kJ / 70 kJ It took 100 kJ of coal to produce the 35 kJ of useful energy in your home. What is the total efficiency?•A: 65%•B: 330%•C: 30%•D: 70%•E: 35% - Correct Ans Answer: E35 kJ/100 kJ If Power plant power generation is 70% efficient and home energy use is raised from 50% to 90%, what is the new process efficiency? A). 60 B). 90 C). 70 D). 10 E). 35 - Correct Ans- Kevin wants to use less fossil fuel by purchasing an electric vehicle. EV's are currently about 50% efficient. •Part 1: The power in Kevin's neighborhood comes from a coal-fired power plant. When Kevin plugs his EV in at night, what is powering his car?• A: Elon Musk• B: Electricity• C: Coal• D: Petroleum• E: Batteries - Correct Ans-C Kevin wants to use less fossil fuel by purchasing an electric vehicle. EV's are currently about 50% efficient. •Part 2: The grid is about 20% efficient and Kevin's EV is about 50% efficient. What is the total efficiency of this process?• A: Elon Musk• B: 10%• C: 50%• D: 20%• E: Batteries - Correct Ans-Answer: B 20%*50% The PSU Natural Gas plant produces 7 MW of power. EGEE 101 EGEE 101 Part 1: If it runs at 70% efficiency, what is the rate of energy input? •A: 7 MW•B: 3 MW•C: 70 MW•D: 10 MW•E: 100 MW - Correct Ans-Answer: D If efficiency = useful energy/total energy, then Total energy = useful energy/efficiency = 7 MW/0.70 = 10 MW The PSU Natural Gas plant produces 7 MW of power. Part 1: If it runs at 70% efficiency, what is the rate of energy input? •D: 10 MW Part 2: What if PSU could successfully reuse 1/3rd of the remaining rejected heat...what is the new process efficiency? A: 67%B: 70%C: 80%D: 33% - Correct Ans-answer: CWasted power was 3 MW. Using 1/3rd means 8 MW are useful and 2 MW are wasted. Since total power is 10 MW, efficiency = 8 MW/10 MW In 2016 the U.S. used 97.3 Quads of energy. 66.4 quads were rejected energy. What is the us energy efficiency? •A: 68%•B: 97.3%•C: 32%•D: 66.4%•E: 30.8% - Correct Ans-Answer: C 30.9 Quads useful / 97.3 Quads total Make sure you bring your calculator to the exam Doubling time A population of pets is growing exponentially 1% per year. How many years until the population doubles? •A: 6.93 years•B: 100 years•C: 1 year•D: 69.3 years•E: get your pets spayed or neutered - Correct Ans-Answer: DDoubling time = 0.693/rate = 0.693/.01 = 69.3 Which has a more kinetic energy? a). a cubic mile of water (a lake) behind a 300 ft tall dam b). a car moving at 120 mph across the Bonneville Salts Flats c). an oil tanker moving through the Suez Canal d). an atomic bomb in a silo in North Dakota - Correct Ans-B). The rest of the options have zero velocity KE= 1/2 mv2 what primary energy resources contributes the most to the production of electricity? - Correct Ans-coal 52% for US EGEE 101 EGEE 101 In a power plant, chemical energy is converted to what useful end product? - Correct Ans-electrical: Chemical Energy is converted into thermal energy in the boiler, which is then converted to mechanical energy in the turbine followed by generation of electricity by the generator. T or F: Electric current is a measure of flow of electric charge - Correct Ans-True T or F: Electric power is measured in terms of voltage. - Correct Ans-False: Unit of electric power is watts Electric power is measured as - Correct Ans-Voltage multiples by current What is the function of a generator in a power plant? - Correct Ans-b. Convert mechanical energy to electrical energy What is the energy conversion that takes place in a turbine in a power plant? - Correct Ans-thermal- mechanical In a gas turbine power plant, which fuel is burned to run the turbine? - Correct Ans natural gas t or f: Wind turbine converts the kinetic energy of air into mechanical energy through the rotation of blades. - Correct Ans-true t or f: In a nuclear power plant, nuclear reactions are us