Questions and Answers of Exploring Engineering Introduction

An industrial fuel cell has to supply a continuous 20. MW to a perfectly efficient inverter at 123.V. Assuming it uses a hydrogen gas/air/PEM system, what are the needed flows of H2 and air to the
Consider a graph of the half cell potentials in Table 8.2 vs. the density of the electrode metal in the half cell. Explain whether or not it is possible to design a cell that is both light and high
Compare a battery made from the following pairs of aqueous half cells: Mg++ + 2e- ↔ Mg(s) and Cu++ + 2 e- ↔ Cu(s) with Fe++ + 2 e- ↔ Fe(s) and Ag+ + e- ↔ Ag(s). What will be the voltages and
Design a battery pack composed of D-cells (6.35 cm long x 3.18 cm diameter each weighing 0.100 kg). The final package (see diagram) must supply 42.0 V (the coming standard for all cars) at 30.0 A for
Design a battery pack composed of D-cells (6.35 cm long x 3.18 cm diameter each weighing 0.100 kg). The final package (see diagram) must supply 42.0 V (the coming standard for all cars) at 30.0 A for
Design a battery pack composed of D-cells (6.35 cm long × 3.18 cm diameter each weighing 0.100 kg). The final package (see diagram) must supply 42.0 V (the coming standard for all cars) at 30.0 A
Will a Ragone chart confirm the conclusions of exercise 4? Describe how by referencing Figure 8.6. How long to discharge the ultracapacitor?Figure 8.6. 1,000 Lead-acid 100 Fuel Cells NİMH 10 Ultra-
In a proposed hybrid car, the battery is reinforced by an ultracapacitor with the following characteristics: 5.0 Wh/kg and 5.0 kW/kg. If the car wants to draw upon its ultracapacitor for 10. kW for
You wish to store 2.00 MWh as an emergency power supply for a “big-box” store. If the gross energy storage density of the battery is 425 kJ/liter how big is the storage battery in m3? If the
A windmill produces mechanical power according to this formula: P = 1/2ηrV3A where Z is its efficiency (assume Z = 60.%), r = density of air (1.00 kg/m3), V = wind speed in m/s (assume 5.0 m/s), and
A vehicle has a 15. US gallon gas tank and can be filled from empty in 60. seconds.a. What is the rate that power is transferred to the vehicle?b. If the vehicle is converted to an all-battery system
A female student in your class mentions to you that she is being sexually harassed by another student. What do you do?a. Do nothing; it is none of your business.b. Ask her to report the harassment to
It is the last semester of your senior year and you are anxious to get an exciting electrical engineering position in a major company. You accept a position from company A early in the recruiting
Determine the currents I1, I2, I3, and I4 in the following figure. 6.0 Ohms 12. Ohms 9.0 Ohms 9.0 Ohms 45. V
Repeat Example 7.7 with V1 increased to 100. volts and V2 reduced to 5.0 volts.Example 7.7Find the current through and voltage across the 40. ohm resistor, R3, in the following circuit. Need: I3
Repeat Example 7.7 with the resistor R1 changed to 100. ohms and all other values unchanged.Example 7.7Find the current through and voltage across the 40. ohm resistor, R3, in the following
Determine the currents I1 and I2 in the current divider illustrated in Figure 7.7 if V = 50.3 volts, R1 = 125. ohms, and R2 = 375. ohms.
If the resistors in exercise 23 are all equal to 10. ohms (R1 = R2 = R3 = 10. ohms), what is the current supplied by the 6.0 volt battery?Exercise 23Use Kirchhoff’s voltage and current laws to
Use the same RadioShack stock resistors in Example 7.6 to design the construction of a voltage divider that will reduce the voltage by a factor of 30.Example 7.6Suppose you want to build a voltage
Use Kirchhoff’s voltage and current laws to determine the voltage drop and current in each of the following three resistors if R1 = 10. ohms, R2 = 20. ohms, and R3 = 30. ohms. + R2 R3 + R1 6.0 V +
Determine the output voltage, Vout, in Figure 7.5 if Vin = 90. V, R1 = 10. ohms, and R2 = 50. ohms.
Consider the circuit shown with exercise 9. What are the currents I0 through I6? What are the voltages Va and Vb? Note the symmetry between R1/R2 = 5.0/5.0 and R3/R4 = 10.0/10.0. 12 V lo 13 5.0 Ω |
Suppose a car has headlights operating in parallel but with different resistances—one of 2.0 ohms and the other of 3.0 ohms. Suppose the headlight parallel circuit is connected in series with a
Suppose one of the headlights in exercise 17 suddenly burns out. Will the power produced by the other headlight increase or decrease?Draw the circuit and solve for the unknown quantity
An automobile’s 12. V battery is used to light the automobile’s two headlights. Each headlight can be modeled as a single resistor. If the two headlights are hooked up to the battery in parallel
An automobile’s 12. V battery is used to light the automobile’s two headlights. Each headlight can be modeled as a 1.00 ohm resistor. If the two headlights are hooked up to the battery in
An automobile’s 12. V battery is used to light the automobile’s two headlights. Each headlight can be modeled as a 1.00 ohm resistor. If the two headlights are hooked up to the battery in series
An automobile’s 12. V battery is used to drive a starter motor, which for several seconds draws a power of 3.0 kW from the battery. If the motor can be modeled by a single resistor, what is the
Acircuit consists of a 12. volt battery attached to a 1.0 × 102 ohm resistor, which is in turn connected to two parallel branches, each containing a 1.0 × 103 ohm resistor. Find the current drawn
A circuit consists of a 9.0 volt battery and two parallel branches, one containing a 1500 ohms resistor and the other containing a 1.0 x 103 ohm resistor. Find the current drawn from the battery.Draw
A circuit consists of a 12. V battery and a resistor connected in series with it. The current is 105. A. Find the resistance.Draw the circuit and solve for the unknown quantity requested.
A circuit consists of a 3.0 V battery and two resistors connected in series with it. The first resistor has a resistance of 10. ohms. The second has a resistance of 15. ohms. Find the current in the
For the circuit shown, a power of 100. watts is dissipated in each resistor. Find the current I and the voltage V. 60. Ω ν 12
For the circuit shown, find the resistance R.The circuit for this exercise is given in the table. | = 15 A 100. Q 100. 2 12V Exercise 1 Exercise 2 | = 1.5 A R R 12V 12V Exercise 3 Exercise 4 | 50. A
For the circuit shown, find the voltage V.The circuit for this exercise is given in the table. | = 15 A 100. 2 100. Ω 12V Exercise 1 Exercise 2 1 = 1.5 A R R 12V 12V Exercise 3 Exercise 4 1 = 50. A
For the circuit shown, find the current I.The circuit for this exercise is given in the table. | = 15 A 100. 2 100. Ω 12V Exercise 1 Exercise 2 1 = 1.5 A R R 12V 12V Exercise 3 Exercise 4 1 = 50. A
For the circuit shown, a power of 100. watts is dissipated in the resistor. Find the resistance, R.The circuit for this exercise is given in the table. | = 15 A 100. 2 100. Ω 12V Exercise 1 Exercise
For the circuit shown, a power of 100. watts is dissipated in the resistor. Find the current I.The circuit for this exercise is given in the table. | = 15 A 100. 2 100. Ω 12V Exercise 1 Exercise 2 1
For the circuit shown, find the resistance R.The circuit for this exercise is given in the table. | = 15 A 100. 2 100. Ω 12V Exercise 1 Exercise 2 1 = 1.5 A R R 12V 12V Exercise 3 Exercise 4 1 = 50.
For the circuit shown, find the current I.The circuit for this exercise is given in the table. | = 15 A 100. 2 100. Ω 12V Exercise 1 Exercise 2 1 = 1.5 A R R 12V 12V Exercise 3 Exercise 4 1 = 50. A
For the circuit shown, find the voltage V.The circuit for this exercise is given in the table. | = 15 A 100. Q 100. 2 12V Exercise 1 Exercise 2 | = 1.5 A R R 12V 12V Exercise 3 Exercise 4 | 50. A R
As an engineering student you are offered a lucrative summer job at a large tire manufacturing company. On your first day of work you are asked to sign an agreement assigning to the company all
As a young engineer in the transmission division of a large automotive company, you are given an engineering assignment that originated in the engine division. Your supervisor is experienced and has
What is the Gasoline Gallon Equivalent of 5.0 gallons ofa. Diesel fuelb. E-85c. Compressed natural gas at 3000 psid. Liquid natural gas (LNG)
Using a spreadsheet analysis, plot the annual cost of fuel for the vehicle in Example 6.4 as the cost of gasoline ranges from $1.00 to $10.00 per gallon.Example 6.4The cost of fuel is rising and you
For the conventionally powered vehicle in Example 6.4 weighing 2,750 lbf and ranging 12,000 miles/ year, what is the total annual cost of fuel if it costs $10.00 per gallon?Example 6.4The cost of
Estimate the amount of water to generate H2 if all the cars in the United States were hydrogen powered fuel cell vehicles. Assume a vehicle fuel economy of 60. miles per kg of hydrogen, total vehicle
A gas turbine engine has been developed with a compressor pressure ratio of 6.7. What is the Brayton cycle efficiency of this engine?
What pressure ratio would be required to produce a Brayton cycle efficiency of 75 percent?
What would the Brayton cycle efficiency in Example 6.3 be if the pressure ratio was increased to 3.5?Example 6.3A jet engine needs to produce only enough net output power to drive the aircraft’s
Using highly advanced materials, a research laboratory has produced a new Diesel cycle engine with a compression ratio of 58.9 and a cut-off ratio of 3.9. What is the Diesel cycle efficiency of this
Determine the Diesel cycle efficiency of an engine that has a compression ratio of 18.6 and a cut-off ratio of 2.2.
What would the ideal power produced by the Diesel engine in Example 6.2 be if the air-to-fuel ratio was changed to 25?Example 6.2A new four-cylinder, four-stroke Diesel cycle engine with a
What would the Diesel cycle engine efficiency in Example 6.2 be if the cut-off ratio was reduced to 1.9?Example 6.2A new four-cylinder, four-stroke Diesel cycle engine with a compression ratio of
The power output of the lawnmower engine is not directly proportional to the number of RPMs, as the simple formula Equation (6.1) suggests. It actually reaches a peak at about N = 2500 RPM and
Based on your measurements so far, if the mechanical efficiency of the lawnmower engine is 0.50, what is the power output of the lawnmower engine, in kW, when it is operating at 2.50 x 103 RPM with a
Based on your measurements and calculations so far, what is the Otto efficiency of the lawnmower engine?Refer to a 3.5 horsepower lawn mower engine at a nominal speed of 2.50 × 103 RPM. A
If available, based on your measurements of bore (cylinder diameter), stroke (TDC to BDC), and clearance volume, CV, what is the displacement,D, of the lawnmower engine? (Use experimental numbers if
Based on your measurements and calculations (exercise 13), what is the compression ratio, CR, of the lawnmower engine?Refer to a 3.5 horsepower lawn mower engine at a nominal speed of 2.50 ×
To get an idea of how realistic it would be to build an Otto cycle engine with the displacement you calculated in exercise 11, assume that your engine had cylinders each the size of a two-liter soft
You are attending a national engineering conference as a representative of your company. A supplier to your company has a booth at the conference and is passing out small electronic calculators to
Suppose you wanted to design an Otto cycle engine with the same power output as the two jet engines powering the fire truck. Suppose your Otto cycle engine was able to achieve the far higher
Suppose the fuel used by the fire truck contains 45,500 kJ/kg of chemical energy. What is the overall efficiency (ratio of mechanical power out to chemical power in) of the truck’s engines?Involve
The derivation of Equation (6.1) relies on the method of canceling units in brackets [. . .] as in the following steps. Replace each of the steps in words with its dimensionally correct mathematical
For the engine in exercise 6, suppose you wanted to increase the power output at 4.00 × 103 RPM by 50 percent while retaining a compression ratio of 9.0. One way to do this would be by changing only
For the engine in exercise 6, suppose you wanted to increase the power output at 4.00 x 103 RPM by 10 percent. One way to do this would be by changing only the compression ratio. What would the new
An Otto cycle engine has a total displacement of 0.0040 m3. Its compression ratio is 9.0. It is fueled with gasoline having a specific heating value of 45,500 kJ/kg. Its mass air-to-fuel ratio is
Suppose you want to design an Otto cycle engine with a thermal efficiency of 45 percent. What compression ratio must you use?
An Ottocycle engine has a compression ratio of 8.0.What is the engine’s thermal efficiency? (A: 0.56 or 56%)
What would be the ideal power produced in Example 6.1 if the engine had a turbocharger that boosted the inlet air density to 3.7 kg/m3?
What would be the ideal power produced in Example 6.1 if the engine’s total displacement was 8000. cm3 and it was running at 3000. RPM?Example 6.1A new four-cylinder Otto cycle engine has a total
What would be the Otto cycle efficiency in Example 6.1 if the engine’s compression ratio was 10.0?Example 6.1A new four-cylinder Otto cycle engine has a total displacement of 5000. cm3 and a
It is 2021 and you are a process engineer at a large oil refining company. The world is rapidly moving toward a hydrogen energy economy and your company has been trying to develop an efficient and
It is December 1928 and your name is Thomas Midgley, Jr.21 You have just invented a new miracle refrigerant composed of chlorinated fluorocarbons (CFCs) that will make your company a lot of money. At
As a production engineer for a large chemical company, you need to find a new supplier for a specific commodity. Since this contract is substantial, the salespeople with whom you meet are naturally
You have worked for a petroleum company producing automotive fuels for several years, and in your spare time at home you have developed a new fuel composition that has a higher heating value than
The glass pipe system shown below has a liquid flowing in it at an unknown rate. The liquid is very corrosive and flow meters are correspondingly very expensive. Instead you propose to your boss to
A crude oil contains just three components by weight: 15.% asphaltenes, 1.0% light gases (containing about 1 – 5 carbon atoms þ hydrogen) and the remainder light distillate that is pure isooctane.
A pipe carries a mixture of, by kmols (which are proportional to the number of molecules), 15.% C5H12, 25.% C8H18, 50.% C16H34, and 10.% C32H40. What is the percentage of each substance by mass?
In 1800 the main fuel used in the United States was wood. (Assume wood is cellulose, whose representative repeating formula is C6H12O6.) In 1900, the main fuel used was coal (assume coal in this
Given the heat of formation of liquid methanol, CH3OH(l), is 238,000 kJ/kmol, what is its heat of combustion in kJ/kg?
Repeat exercise 19 for the combustion of coal. For simplicity assume coal is just carbon, C, with a HV of 32,800 kJ/kg.Use engineering considerations to give insight on the global warming
A monomeric formula for wood cellulose is C6H12O6 (it repeats many times as a hexagonal structure based on this formula). The energy content by burning wood is approximately 1.0 × 104 J/kg.
Give three reasons why your suggested solution in exercise 17 to global warming has not already been adopted.Use engineering considerations to give insight on the global warming issue.
The amount of carbon dioxide levels in the atmosphere has been increasing for many decades. Many scientists believe that the increase in carbon dioxide levels could lead to global warming, and might
Assume a kg of hydrogen in combustion produces 1.20 × 105 kJ of thermal energy. How much carbon dioxide is released in obtaining a kJ of energy from the combustion of hydrogen in air?Use engineering
Assume one kg of isooctane produces 45,500 kJ of energy. How much carbon dioxide is released in obtaining a kJ of energy from the combustion of isooctane in air? (A: 6.79 × 10 5 kg CO2/kJ)Use
Determine the mass air-to-fuel ratio (A/F)mass for the combustion of isooctane C8H18 in air. Its stoichiometric equation isC8H18 + 12:5(O2 + 3:76N2) = 8CO2 + 9H2O + 47:0N2
Determine the mass air-to-fuel ratio (A/F)mass for the combustion of coal in air represented by the equation:CHN0:01O0:1S0:05 + a(O2 + 3:76N2) = bCO2 + cH2O + dN2 + eSO2
Determine the mass air-to-fuel ratio (A/F)mass for the combustion of an oil (represented by CH2) in air.
Using the results of exercises 9 and 10, determine the mass air-to-fuel ratio (A/F)mass for the combustion of natural gas in air. (A: 17.2 kg of air/kg of fuel)
Using the stoichiometric coefficients you found in exercise 9, determine the molar air-to-fuel ratio (A/F)molar for the combustion of natural gas in air. (A: (A/F)molar = 9.52 kmol of air/kmol of
Determine the value of the stoichiometric coefficients for the combustion of natural gas in air:CH4 + a(O2 + 3:76N2) = bCO2 + cH2O + dN2
Determine the value of the stoichiometric coefficients for the combustion of coal in oxygen given by the stoichiometric equation:CHN0:01 O0:1S0:05 + aO2 = bCO2 + cH2O + dN2 + eSO2
Determine the value of the stoichiometric coefficients for the combustion of an oil (assumed molecular formula CH2) in oxygen: CH2 + aO2 = bCO2 + cH2O. Confirm your answer is correct! (A: a = 1.5, b
A gallon of gasoline has a mass of about 3.0 kg. Further, a kg of gasoline has an energy content of about 45,500 kJ/kg. If an experimental automobile requires just 10. kW of power to overcome air
The effective molecular mass of air is defined as the mass of a kmol of elementary particles of which 78.09% are nitrogen molecules, 20.95% are oxygen molecules, 0.933% are argon atoms, and 0.027%
What is the mass of 1.00 kmol vitamin B1 disulfide, C24H34N8O4S2?
What is the mass of 5.0 kmol of carbon dioxide, CO2? (A: 2.2 × 102 kg)
How many kmol are contained in 1.0 kg of nitroglycerine, C3H5(NO3)3?

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