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EGEE FINAL EXAM 250 QUESTIONS & CORRECT ANSWERS WITH RATIONALES (WELL VERIFIED) GRADED A+
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What type of energy would each of the following be? A barrel of oil The sun beating down a solar panel A piston moving in a car engine - CORRECT ANSWER >>> A barrel of oil - Chemical energy The sun beating down a solar panel - Thermal energy A piston moving in a car engine - Mechanical energy A steel rod is initially very cold. If it is placed close to a fire, what happens? A) The steel rod heats up. B) The fire goes out. C) Nothing happens. - CORRECT ANSWER >>> A) The steel rod heats up. Which do you think is more efficient? A) A jet engine that produces 70 units of work from 100 units of energy. B) A vehicle that produces 50 units of work from 100 units of energy. C) A water mill that produces 10 units of work from 100 units of energy. **- CORRECT ANSWER
** A) A jet engine that produces 70 units of work from 100 units of energy.
There are a little more than 7.5 billion people on the planet today, but 2.5 billion people are using most of the energy. The UN projects that human population will stabilize around 10 billion people by the year 2100 - an addition of 2.5 billion more people. How much would energy use increase by if 10 billion people in 2100 are using the amount of energy 2.5 billion people are using today? A) 4x B) 2x C) 1x D) 3x - CORRECT ANSWER >>> A) 4x Through a combination of fertility rate and decreased poverty levels, a population's energy use is growing exponentially 1% per year. How many years until the energy use doubles? - CORRECT ANSWER >>> 69.3 years t= 0.693/rate = 0.693/0.01 = 69.3 years What energy growth rate per year would increase world energy use by 400% (2 doubling periods) in 80 years? - CORRECT ANSWER >>> 1.7 per year t=0.693/rate --> rate=0.693/time rate= 0.693/40 = 1.7% per year A wind turbine costs $10 million to construct and generates $1 million worth of electricity per year. When has the wind turbine paid for itself (what is the pay-back period)? - CORRECT ANSWER >>> 10 years
Which has more nuclear energy? A) An oil tanker moving through the Suez Canal. B) A cubic mile of water (a lake) behind a 300 ft tall dam. C) An atomic bomb in a silo in North Dakota. D) A car moving at 120 mph across the Bonneville Salt Flats. - CORRECT ANSWER >>> C) An atomic bomb in a silo in North Dakota. Which has more chemical energy? A) An oil tanker moored at a terminal. B) A cubic mile of water (a lake) behind a 300 ft tall dam. C) An atomic bomb in a silo in North Dakota. D) A car moving at 120 mph across the Bonneville Salt Flats. - CORRECT ANSWER >>> A) An oil tanker moored at a terminal. The hot coffee heats the mug which heats my hands which are holding the mug. What method of heat transfer is it? - CORRECT ANSWER >>> Conduction What transformation occurs in the Sun? - CORRECT ANSWER >>> Nuclear to radiation What transformation occurs in a computer? - CORRECT ANSWER >>> Electrical to light/sound What transformation occurs in a lawn mower? - CORRECT ANSWER >>> Chemical to kinetic/mechanical
A power plant consumes 100 MJ of Energy, of which only 24 MJ are wasted heat. What is the efficiency? - CORRECT ANSWER >>> 0. Efficiency = (Etotal-Ewaste)/Etotal = (100-24)/100 = 76% A power plant converts 100 kJ of coal into 30 kJ of electrical energy. What is the efficiency? - CORRECT ANSWER >>> 30% Efficiency = Eout/Etotal = 30/100 = 30% Your home converts 30 kJ of electrical energy into 15 kJ of useful energy (heat, electric) and 15 kJ of wasted energy. What is your home's efficiency? - CORRECT ANSWER >>> 50% Efficiency = Eout/Etotal = 15/30 = 50% It took 100 kJ of coal to produce the 15 kJ of useful energy in your home. What is the total efficiency? - CORRECT ANSWER >>> 15% Efficiency = Eout/Etotal = 15/100 = 15% The Penn State natural gas plant produces 7 MW of power. If it runs at 70% efficiency and has 7MW Power Out, what is the rate of energy input? - CORRECT ANSWER >>> 10 MW
20% x 50% = 10% Kevin wants to use less fossil fuel by purchasing an electric vehicle. EV's are currently about 50% efficient. Gasoline engines are about 25% efficient. What is better for Kevin's wallet and for the environment? - CORRECT ANSWER >>> 25% overall efficient use of gasoline Kevin lives next to a coal fired power plant. He wants to be greener, so he buys an electric vehicle, which he charges with his home's electricity. Is Kevin helping the environment? - CORRECT ANSWER >>> No, the process efficiency and carbonized power grid make Kevin's EV dirtier than an IC (internal combustion) vehicle. In 2019 the U.S. used 100.2 quads of energy out of which 67.5 quads were rejected energy. What is the US energy efficiency? - CORRECT ANSWER >>> 32% Efficiency = (Etotal-Ewaste)/Etotal = (100.2-67.5)/100.2 = 32% Chose the answer that lists the electromagnetic wave radiant energy forms in order, from longest wavelength to shortest, from lowest frequency to highest. - CORRECT ANSWER >>> AM radio, microwave oven, heat from a person or pet, incandescent light bulb, UV - black light, dental X rays, gamma rays from a radioactive element Heat energy spontaneously migrates from areas of higher temperature to areas of lower temperature. Match each method of heat transfer with its description. **- CORRECT ANSWER
** Heat flows from warmer to cooler by contact between the materials. The hot coffee heats the mug which heats my hands which are holding the mug. - Conduction Heat flows from one place to another because the heated material itself moves. The warm
winds blow and heat from the tropics ends up in Pennsylvania. - Convection
An object loses heat to the environment via electromagnetic waves. The wavelength of these waves is determined by the temperature of the object, with cooler objects giving off longer wavelengths. - Radiation Some outdoor security lights are kept on overnight - 7 hours. They use 225 watts of power (figure out how much energy do they consume). If electricity costs $.10 per kilowatt hour, what is the electricity cost for these lights? Please include two decimal places in your answer. - CORRECT ANSWER >>> 0. (225)(7) = 1,575 wh = 1.575 kwh --> 1.6 kwh Match each of the basic types of energy with its definition. - CORRECT ANSWER >>> Kinetic energy: The energy of moving things. Potential Energy: The energy an object has due to its position. Nuclear energy: The energy released when atomic nuclei split or fuse. Thermal energy: The energy of heat or temperature. Radiant energy: Energy transmitted via electromagnetic waves Chemical energy: Energy stored in the bonds between atoms Electrical energy: The energy of flowing electrons Units of energy? - CORRECT ANSWER >>> BTU, kilowatt hour, joule, calorie
Very hot, high pressure steam spins a turbine. - CORRECT ANSWER >>> Heat to Kinetic A plant's leaf makes sugar in the afternoon. - CORRECT ANSWER >>> Radiant to Chemical A star shines in space. - CORRECT ANSWER >>> Heat to Radiant Choose the answer that lists the correct sequence of steps in the process of turning a fuel into electricity that is available in your home. - CORRECT ANSWER >>> A fuel is burned in a boiler. Water absorbs heat and boils into steam. High-pressure steam is directed through a turbine, causing it to spin. A turbine spins an electric generator, pushing electrons through wires. A step-up transformer reduces the current and raises the voltage. High-voltage power lines distribute the electric power to distant locations. A step-down transformer reduces the voltage and raises the current. A ball of mass 2 kg is placed at position A at a height of 50 m from the ground. The initial velocity is 0 m/s. If the ball starts rolling down an inclined plane, what are the potential and
kinetic energies at positions A, B, C and D in Joules assuming that the ball does not experience any frictional force (total mechanical energy does not change)? Please use 9.8 m/s2 for the gravitational constant when calculating potential energy. The heights of positions A, B, C, and D are listed below: A: 50 meters B: 25 meters C: 25 meters D: 0 meters What is the velocity of the ball in meters per second when it reaches point B or C (round to the nearest whole number)? - CORRECT ANSWER >>> Potential @A 980 Kinetic @A 0 Potential @B 490 Kinetic @B 490 Potential @C 490 Kinetic @C 490 Potential @D 0 Kinetic @D 980 Velocity of the ball: 22 Which of the following is not a unit of energy? A) BTU
C) Foot D) All of the above - CORRECT ANSWER >>> A) Joules What is the form of energy in a flying airplane? A) Electrical B) Radiant C) Mechanical D) Chemical - CORRECT ANSWER >>> C) Mechanical Energy that is locked in the nucleus of an atom and is released by destruction of mass can be calculated as A) E=mgh B) E=1/2mv^ C) E=mc^ D) None of the above - CORRECT ANSWER >>> c) E=mc^ What is the energy stored in the bonds that hold molecules together called? A) Nuclear B) Chemical C) Thermal D) Kinetic - CORRECT ANSWER >>> B) Chemical How many calories is 1 food calorie equivalent to? A) 100 B) 1000 C) 1,000, D) 10,000 - CORRECT ANSWER >>> B) 1,
Energy can be converted from one form to another. A) True B) False - CORRECT ANSWER >>> A) True Wavelength is used to classify what type of energy? A) Mechanical B) Chemical C) Radiant D) Nuclear - CORRECT ANSWER >>> C) Radiant In what direction does thermal energy flow? A) independent of the temperature difference B) in both directions C) From low temperature to high temperature D) From high temperature to low temperature - CORRECT ANSWER >>> D) From high temperature to low temperature Energy possessed by a body due to its motion is called A) Thermal B) Kinetic C) Chemical D) Potential - CORRECT ANSWER >>> B) Kinetic What is the form of energy that is present in pizza that we eat?
C) increases D) decreases - CORRECT ANSWER >>> C) Increases What is the form of energy contained in a battery? A) Electrical B) Chemical C) Potential D) Kinetic - CORRECT ANSWER >>> B) Chemical Which of the following is NOT a basic need of a human being? A) Air B) Food C) Water D) Shelter E) None of the above - CORRECT ANSWER >>> E) None of the above Which of the following is the process of breaking a large nuclei into two intermediate size nuclei? A) Chemical reaction B) Nuclear fusion C) Nuclear fission D) All of the above - CORRECT ANSWER >>> C) Nuclear Fission
What property of a small meteor falling from the sky causes a lot of damage when it hits the earth? A) High heat energy B) High Potential energy C) Explosive Chemical energy D) High Kinetic energy - CORRECT ANSWER >>> D) High kinetic energy What is the type of energy contained in the water stored behind a dam? A) Electrical B) Kinetic C) Chemical D) Potential - CORRECT ANSWER >>> D) Potential Energy is a property of matter that can be converted into work, heat or radiation. A) True B) False - CORRECT ANSWER >>> A) True Energy can be created or destroyed. A) True B) False - CORRECT ANSWER >>> B) False Work can be converted to heat or thermal energy.
A woman moves a box through a distance of 10 m. What is the work done if the force applied is 10N? A) 100 J B) 50 J C) 0 J D) None of the above - CORRECT ANSWER >>> A) 100 J Which famous scientist proposed the equation E=mc^ A) Newton B) Galileo C) Joule D) Einstein - CORRECT ANSWER >>> D) Einstein The unit of electrical energy is A) Joules B) Newton C) Kilowatt-hour D) Electron-volt - CORRECT ANSWER >>> C) Kilowatt-hour Which of the following is the only direct use of electrical energy without converting it to another form? A) Defibrilator
B) Light bulb C) Laptop D) Heater - CORRECT ANSWER >>> A) Defibrilator What is the type of energy that a body possesses by virtue of its physical position? A) Radiation B) Potential C) Kinetic D) Thermal - CORRECT ANSWER >>> B) Potential Which one of the following is not a mode of heat transfer? A) Translation B) Convection C) Conduction D) Radiation - CORRECT ANSWER >>> A) Translation What happens to the r-value of the insulation if the thickness increases? A) remains same B) increases C) decreases D) R-value is independent of thickness of insulation - CORRECT ANSWER >>> B) Increases