Questions and Answers of Exploring Engineering Introduction

A car leaves a parking space from a standing stop to travel to a fast-food restaurant 950 meters away. Along the journey it has to stop after 325mat a stop sign. It has a maximumacceleration of
Based on your experience as a driver or a passenger in a car, estimate (with calculations) the maximum deceleration achieved by putting maximum pressure on the brakes when traveling at 30 mph.
For the previous problem, supply a table and draw a graph showing the distance, speed, and acceleration of the car versus time.Use the v-t diagram for this exercises.Previous problem 15 m/s v, m/s d=
A car starts from a stop at a traffic light and accelerates at a rate of 4.0 m/s2. Immediately on reaching a speed of 32. m/s, the driver sees that the next light ahead is red and instantly applies
A car is alone at a red light. When the light turns green, it starts off at constant acceleration. After traveling exactly one-eighth of a mile, it is traveling at 30. mph. What is its acceleration
A car is alone at a red light. When the light turns green, it starts off at constant acceleration. After traveling 100. m, it is traveling at 15. m/s. What is its acceleration?Use the v-t diagram for
Sara, a recent graduate, accepts a position at a small engineering design firm. Her new colleagues form a tightly knit, congenial group, and she often joins them for get togethers after work. Several
Part of the mechanism of a toilet is the system that refills the toilet tank after a flush. A conceptual sketch is shown below. Water enters the tank through an annular opening around the plug;
A steam reformer is fed 1.00 liters/s of methane, 0.952 liters/s of air, and 1.00 liters/s of steam. If it reaches its stoichiometric maximum extent of reaction, what is the composition of its
Consider the following electric circuit: Consider the variables L = “the light is on,” A = “switch A is closed,” and B ¼ “switch B is closed.” Express the relationship depicted by the
Draw lines of constant discharge time on the Ragone plot. Interpret these lines. Energy/power = time. On a log-log plot since time is represented only to the first power, its slope is 1, which is
Download the West Point Bridge Designer software from http://bridgecontest.usma.edu and use it to design a truss.
Depending on which of Exercises 7 through 12 you have completed, determine the required crosssectional areas of the members comprising one or more of the following structures. Assume steel members
Depending on which of Exercises 7 through 12 you have completed, determine the overall factor of safety of one or more of the following structures. Assume steel members with a yield strength of SY =
Calculate the required cross-sectional areas of the members comprising the truss bridge of Figure 12.14. Refer to Figure 12.17 for the forces and design for a factor of safety of N = 5.0. Assume
Calculate the overall factor of safety of a truss that has the member forces, lengths, and cross sectional areas given in the table. Assume steel members (SY = 36.×106 lbf/in2, E = 29. ×
A truss that is pinned at one end and on rollers at the other will be statically determinate if it satisfies the following equation:0 = 2j - m - 3where j is the number of joints and m is the number
Determine the forces on all members by the method of joints. Use Excel to solve the equations. 4.00 ft B D 4.00 ft E F H G 800. Ibf 800. Ibf 1600. Ibf 4.00 ft 4.00 ft 4.00 ft 4.00 ft
Determine the forces on all members by the method of joints. Use Excel to solve the equations. B 10.0 ft А D F 1000. Ibf 1000. Ibf 7.00 ft 7.00 ft '7.00 ft E.
Determine the forces on all members by the method of joints. Use Excel to solve the equations. C D 4.00 m A E 8.00 kN 4.00 m 4.00 m B.
Determine the forces on all members by the method of joints. Use Excel to solve the equations. 3.00 m A E 5.00 kN 3.00 m 3.00 m
Determine the forces on all members by the method of joints. Use Excel to solve the equations. 900. Ibf A 5.00 ft D 15.0 ft 15.0 ft
Determine the forces on all members by the method of joints. Use Excel to solve the equations. 1000. Ibf 5.00 ft A 7.00 ft 7.00 ft
Photos of four existing bridges are shown. For each bridge, write a paragraph that describes in specific terms the strategies used by the designer to make it an efficient structure. General
For the structure below, do your best to identify all of its members as beams, compression members, or tension members. D E F A G 5.0 kN 5.0 kN cable 10. kN cable
Determine the forces acting on the ends of the rope by (1) drawing the free-body diagram, (2) counting unknowns and equations to check determinacy, (3) writing the equilibrium equations, and (4)
Determine the forces acting on the ends of the rope by (1) drawing the free-body diagram, (2) counting unknowns and equations to check determinacy, (3) writing the equilibrium equations, and (4)
Determine the forces acting on the ends of the rope by (1) drawing the free-body diagram, (2) counting unknowns and equations to check determinacy, (3) writing the equilibrium equations, and (4)
When estimating the live load for a new bridge design, you want that estimate to be conservative. In other words, you want to error on the safe side by basing the estimate on the worst possible
As quality control engineer for your company, you must approve all material shipments from your suppliers. Part of this job involves testing random samples from each delivery and making sure they
Your company wants to enter a new market by reverse-engineering a popular folding kitchen step stool whose patent recently has expired. Your analysis shows that by simplifying the design and making
Suppose a shield exactly 0.01 m thick of the material in exercise 18 exactly met the requirement of surviving without denting or damage at a strain of -0.10, yet any thinner layer would not survive.
Suppose you were required to use a micrometeorite shield no more than 0.01 meters thick. What would be the required toughness of the material from which that shield was made if the shield must
Using the stress–strain properties for a polymer (Figure 11.13 and Table 11.1), determine whether a sheet of this polymer 0.10 m thick could serve as a micrometeorite shield if this time the shield
Using the stress–strain diagram for steel in Figure 11.11, determine the minimum thickness a steel micrometeorite shield would have to be to protect the spacecraft from destruction (even though the
In exercise 14, what is the highest speed the artillery shell can have and still bounce off the armor plate without penetrating it?Imagine the idealized situation as shown in Figure A for an
Which of the following will happen as a result of the collision in the exercise 13? Support your answer with numbers.a. The shell will bounce off without denting the armor plate.b. The armor plate
Assume that the energy transferred in the collision between the shell and the armor plate in exercise 12 affects only the shaded area of the armor plate beneath contact with the flat tip of the shell
Suppose the shell has a mass of 1.0 kg and is traveling at 3.0 × 102 m/s. How much TKE does it carry?Imagine the idealized situation as shown in Figure A for an artillery shell striking an armor
How many coats having the same mass as those in exercise 10 must be hung on the hanger to cause the neck to remain permanently stretched (i.e., plastically deformed) after the coats are
A coat hanger is made from polyvinyl chloride. The neck of the coat hanger is 0.01 m in diameter and initially is 0.10 m long. A coat hung on the coat hanger causes the length of the neck to increase
What is the maximum number of coffee cups in Exercise 8 that can be stacked vertically on the saucer and not cause a permanent dent in the plate?Assume that a silicone rubber19 has this
A flat saucer made of silicon rubber has an initial thickness of 0.0050 m. A ceramic coffee cup of diameter 0.10 m and mass 0.15 kg is placed on the saucer. What is the final thickness of the saucer
What is the yield strength under compression of the silicone?Assume that a silicone rubber19 has this stress–strain diagram. 150 - Stress, MPa 100 50 + -1.5 -1.0 -0.5 0.5 1.0 1.5 -50 Fractional
A plate of elastic modulus 1.00 GPa is subjected to a compressive stress of 1.00 × 103 Pa as in Figure B. What is the strain on the plate?The following figures depict the situations described in
Suppose the wire in Figure A is perfectly elastic. When subjected to a stress of 1.00 × 104 Pa, it shows a strain of 1.00 × 10-5. What is the elastic modulus (i.e., Young’s modulus) of the
Suppose the plate described in exercise 3 and Figure B was 0.011 m thick before the cube was placed on it. Suppose that placing the cube on it causes a compressive strain of -0.015. How thick will
In Figure B, when a block of metal 1.00 m on a side is placed on a metal plate 1.00 m on a side, the stress on the plate is 1.00 x 103 N/m2. What is the mass of the metal cube?The following figures
If the wire in Figure A is stretched from 1.00 m to 1.01 m in length, what is the strain of the wire?The following figures depict the situations described in above exercise. Diameter 0.20 mm L Cube
A mass of M = 1.0 kg is hung from a circular wire of diameter 0.20 mm as shown in Figure A. What is the stress in the wire?The following figures depict the situations described in above exercise.
You are a new engineer working for a motorcycle manufacturer that produces a bike with a known control system instability. This instability can cause the rider to lose control at high speed and
You work for the control and guidance systems division of a major aircraft manufacturer with a major government contract. You observe employees who regularly leave work early while being paid for
Some skeptics have suggested that we are not entering a man-made period of global warming but instead are entering a mini ice age (as Earth has done many times before in its 4+ billion year history).
Referring to Figure 10.12, when a throttle plate rotates in a circular plenum, its effective blocking area is πab where a, b are the principal axes of an ellipse. Show that where A is the fully
In this chapter, we have discussed but not derived, an equation for the transient inertial limited response to engine power and to windage losses. The equation isin which P(engine) and P(losses),
Do you really need a cruise control? Suppose you are driving in the Midwest on a flat road. You are bored with the monotony of the terrain and you set a brick against the accelerator pedal that
Suppose a car employs a digital speed sensor as shown in Figure 10.15, and the car’s wheels are each 0.60 meters in diameter. If the speed sensor consists of the magnet and coil and the magnet
Use the block diagram developed in the previous exercise. Assume the room is initially at T0 = 15°C and the set point for the furnace is 22°C. The furnace heat rate is Q = 1000. W and the room
The conceptual sketch below shows a model of a closed loop control for heat in a room. Prepare a block diagram for this closed loop control. Label each block on the block diagram with the name of the
Suppose that for the open loop toaster control you sketched in exercise 5, the variable that you really want to control is d (for darkness), where d is the energy absorbed by the toast, in units of
The conceptual sketch below shows a model for a closed loop control of a lawnmower engine. Unlike the lawn mower motor of exercise 7, there is a feedback device. It takes advantage of a cooling fan
Suppose a simplified thermostatic room controller operates a furnace that can deliver heat to a room at the rate of 1000. watts. The initial temperature of the room is TR = 20.0°C and the outside
The conceptual diagram and block diagram for open loop control of a 1000. W microwave oven are shown below. (The “magnetron” is the device that delivers the microwaves into the oven’s cavity.)
The conceptual diagram and block diagram of an open loop control for a lawnmower engine are shown below.Assume the control is turned on at time t = 0 and left on thereafter. Use the proportional
The conceptual diagram of an open loop control for the heating of a room is shown below.The room achieves a given temperature as a function of the added heat from the radiator and the heat loss QL
The conceptual sketch for a closed loop control for a toaster is shown below. The controller is a bimetallic switch. It works by combining two metals of different thermal expansion so that, when
The conceptual sketch for an open loop control for a toaster is shown. Draw a block diagram of the system, indicating on the diagram which parts of the conceptual sketch correspond to the blocks.
The following circuit diagram represents a closed loop system for lighting control in an otherwise dark room. Assume you want a lightbulb to provide constant illumination of strength LD even if the
The following circuit diagram is an open loop control for tuning on or off a light. Draw a block diagram of the control. Why is it considered open loop?A: The bulb is on and stays on provided the
You are a software engineer at a small company. You have written a software program that will be used by a major manufacturer in a popular product line. Your supervisor asks you to install a “back
A company purchased a computer program for your part-time job with them. The license agreement states that you can make a backup copy, but you can use the program on only one computer at a time.
In the game “Rock, Scissors, Paper” we have the following rules:Rock breaks ScissorsScissors cut PaperPaper covers RockIf we were to create a code to represent the three entities, Rock, Scissors,
Construct a spreadsheet that converts decimal number 53 to binary. Print as formulae using the Control-tilde command. Check your spreadsheet against exercise 15. 5 (decimal) can be divided by 22
Construct a spreadsheet12 that converts binary numbers from 0 to 111 to decimal numbers, print as formulae using the Control-tilde command. Check your spreadsheet against exercise 14.Exercise
Suppose we want to devise a binary code to represent the fuel levels in a car:a. If we need to describe only the possible levels (empty, 1/4 full, 1/2 full, 3/4 full, and full), how many bits are
If a powerful race car has an (A/F)Mass of 12.0 (kg air)/(kg fuel), and the air intake draws in 1.000 kg of air per second, how much fuel must be injected every second? Solve in binary to three
Do the following binary subtractions. Check your answer by converting each binary number into decimal. Partial A: Binary Decimal Binary Decimal Binary Decimal 1010 10 11101 10000 -110 -6 -10011 -1
Do the following binary additions. Check your answer by converting each binary number into decimal. Partial A: Binary Decimal Binary Decimal Binary Decimal 1010 10 11101 10111 +110 +10011 +10 10000 16
Convert the following numbers from decimal to binary:(a) 53,(b) 446, (c) 1492. Partial A: Decimal 1024 512 256 128 64 32 16 8 4 2 1 210 2° 28 27 26 25 24 23 22 2' 20 Binary place a) 53 1 1 1 1
Convert the following numbers from binary to decimal:(a) 110,(b) 1110, (c) 101011. Partial A: 25 24 23 22 21 20 Decimal Equivalent 32 16 8 4 2 1 - a) 110 0 x 32 0 x 16 0 x 8 1 x 4 1 x 2 0 x1 b)
Explain the following sentences.a. There are 10 kinds of people in the world, those who understand binary numbers, and those who don’t.b. Binary is as easy as 1, 10, 11.
Consider the following logic variables for a car:W = “the seatbelt warning light is on”Ps = “there is a passenger in the passenger seat”Db = “the driver’s seat belt is fastened”Pb =
Consider the following circuit diagram and the variables L = “the light is on,” A = “switch A is closed,” B = “switch B is closed,” and C = “switch C is closed.” Write a logic
Consider the following variables expressing a football team’s strategy.T = “It is third down”L = “We must gain more than 8 yards to get a first down”P = “We will throw a pass”The
Consider the sentence, “If a customer at a restaurant is over 21 and shows proper identification, then she can order an alcoholic beverage.” (a) Express this sentence as a logic equation,
Consider the following logic variables for a car:M = “the motor is running”Db = “the driver’s seat belt is fastened”In the early 1970s the government ordered all seat belt warnings to be
Consider the following logic variables for a car:W = “the seatbelt warning light is on”D = “a door of the car is open”Ps = “there is a passenger in the passenger seat”K = “the key is in
In Example 9.3, include the additional Boolean variable that for actuation of the warning light, “the driver’s door must be closed” (Ddoor is true if the driver’s door is closed).Example
Consider the following logic variables for a car:Db = “the driver’s seat belt is fastened”Pb = “the passenger seat belt is fastened”W = “the seatbelt warning should be on in my
Rework Example 9.2 to express and evaluate the logic formula to answer the question, “If the speed is below the set speed and the set speed is above the speed limit, then will the throttle be
For the ditty in Exercise 1, (a) express as a logic formula the conditions under which one may flush the toilet, (b) evaluate the formula you wrote in (a) for M = 1 and S = 1, and (c) express in
A popular ditty of the late nineteenth- and early twentieth-century railroad era was the following (sung to the tune of Humoresque by the nineteenth-century Czech composer Antonin Dvorak):Passengers
You are the CEO of a company that has developed a new fuel cell invented by one of your company’s most creative engineers. After thoroughly testing the system for safety and reliability under a
You are an engineer on a team developing a radically new battery invented by your immediate supervisor, a successful and famous inventor. Preliminary tests suggest that the new battery, if used in
For the reformer in the two previous questions, what is its maximum electrical power production?Previous two questionsA steam reformer is fed 1.00 liters/s of methane, 0.952 liters/s of air, and 1.00
The same reformer as in the previous problem has a problem—the 3.00 liters/s of H2 is contaminated with 0.600 liters/minute of CO. Assume the shift reactor removes this contaminant down to 10.0 ppm
A methanol fuel cell is used as a battery for a laptop whose average electrical demand is 20. W at 10.0 V. Each cell produces 0.50 V. How much methanol in ml is needed each day? Methanol density is
Solid oxide fuel cells use unique electrolytes—a hard ceramic, based on a solid state solution of zirconium oxide stabilized by the element yttrium, and which will conduct oxygen ions when hot
If you run a fuel cell in reverse as an electrolysis cell, H2O is split into its elementary gases, H2(g) and = O2(g). This way you can make hydrogen and have it stored in case of the loss of outside
In the same fuel cell configuration as in exercise 12, the actual voltage delivered by the cell varies with load; assume the voltage measured at full load is 0.75 V so that the cell electrolytic

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