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The two major forces opposing the motion of a vehicle

Fundamentals of Engineering Thermodynamics | 8th Edition | ISBN: 9781118412930 | Authors: Michael J. Moran ISBN: 9781118412930 139

Solution for problem 2.23 Chapter 2

Fundamentals of Engineering Thermodynamics | 8th Edition

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Fundamentals of Engineering Thermodynamics | 8th Edition | ISBN: 9781118412930 | Authors: Michael J. Moran

Fundamentals of Engineering Thermodynamics | 8th Edition

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Problem 2.23

The two major forces opposing the motion of a vehicle moving on a level road are the rolling resistance of the tires, Fr, and the aerodynamic drag force of the air flowing around the vehicle, Fd, given respectively by Fr f w, Fd CdA1 2 rV2 where f and Cd are constants known as the rolling resistance coefficient and drag coefficient, respectively, w and A are the vehicle weight and projected frontal area, respectively, V is the vehicle velocity, and is the air density. For a passenger car with w 5 3040 lbf, A 5 6.24 ft2 , and Cd 5 0.25, and when f 5 0.02 and 5 0.08 lb/ft3 (a) determine the power required, in hp, to overcome rolling resistance and aerodynamic drag when V is 55 mi/h. (b) plot versus vehicle velocity ranging from 0 to 75 mi/h (i) the power to overcome rolling resistance, (ii) the power to overcome aerodynamic drag, and (iii) the total power, all in hp. What implication for vehicle fuel economy can be deduced from the results of part (b)?

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Chapter 3: Psychoanalytic Approach- Freud  Freud's First Interaction of the Unconscious o Freud not originally a psychologist, but a neurologist o Discovered the unconscious when he began working with another neurologist to eradicate hysterical symptoms in patients using hypnosis o Discovered that hypnosis allowed patients to recall and recount painful, traumatic experiences that were most probably the cause of their hysteric symptoms  Led to the common practice of free association  Allowing the patient to say and talk about whatever comes to their mind o Shifted into the field of psych  Freudian Theory Of Personality o Division of the human personality into three parts  Conscious: thoughts you are currently aware of  Change constantly with new thoughts and stimuli  Small portion of info in our mind  Preconscious: thoughts that you can easily pull into your consciousness  Unconscious: thoughts and memories that you have no immediate access to  Can only bring them into consciousness under extreme situations according to Freud  Is most responsible for your everyday behavior  Called the topographic model  Too limited o Structural Model  Introduces the id, ego, and superego as the three divisions  At birth, one personality structure is present: id  Selfish part of your personality concerned only with the satisfaction of your personal needs and desires  Pleasure principle  Id wants instant gratification  Does not disappear when we grow up, but rather is kept in check by other parts of adult personality  Also operated on wish fulfillment  If what we want or need is not immediately available, the id will imagine what it wants and temporarily satisfy  id is buried entirely in unconscious and is usually associated with sexuality and aggression  Within the first couple years of life, the ego develops  Operated on the reality principle  Primary job of the ego is to satisfy the impulses of the id but in a way that takes into consideration the realities of the world  Must keep the id in the unconscious, as many of its impulses are socially unacceptable  Ego moves freely between the conscious, preconscious, and unconscious parts of your mind  Considers consequences of actions  Superego develops at around 5 years ago  Consists of society's and parent's values and standards  Places more restrictions on what we can and can't do  Brings guilt into the picture  Does not allow us to violate social codes  Can be too little or too much, causing either delinquency or perfectionism  The three constantly compliment and contradict one another  The ego does not allow the id or superego to take over personality o Libido and Thanatos  Human behavior is motivated by strong internal forces or drives  2 distinct types of impulses: life or sexual instinct, death or aggression instinct  Libido: the life or sexual instinct that involves any instinct that has to do with deriving pleasure  Thanatos: death or aggression instinct that refers to our inherent wish to die and return to earth  Is usually outwardly expressed by aggression  The wish to die stays in the unconscious  Freud attributed much of human behavior to libido and Thanatos  Maintained that we have a finite amount of psychic energy  Energy spent on one part of physiological function cannot be used for something else o Defense Mechanisms  Neurotic anxiety: the creepy feeling that unacceptable unconscious thoughts are about to burst through the conscious barrier  Ego has tricks to manage this  Defense mechanisms  Repression: active effort by the ego to force something into the unconscious, causing you to be unaware of it  Happens a lot with traumatic events and memories  Sublimation: channeling threatening impulses into socially acceptable outlets such as sports  More we use this, more productive we are  Only "successful" defense mechanism  Ego doesn’t have to tie up energy holding back the id as it is allowed to dispose of its aggression  Displacement: channeling impulse to non-threatening objects  Freud maintains that our irrational fears and phobias are merely just displacements  Denial: refusing to accept that certain facts exist  Insisting that something is not true despite the evidence that it is true  More we use this, the less in touch with reality  Reaction formation: hide from a threatening unconscious idea or urge by acting in a manner opposite to our unconscious desires  Intellectualization: remove the emotional content from the thought before allowing it into awareness and thinking of it in a purely intellectual way  Bring emotional events up without anxiety  Projection: attributing an unconscious impulse onto other people instead of onto ourselves  By doing so, we free ourselves from the perception that we are the one who actually holds this thought  Psychosexual Stages of development  Freud asserts that our personalities are developed by the time that we are 5 or 6 years old  Psychosexual stages that all children must go through and overcome to develop a healthy personality  Fixation: the inability to pass a certain stage and a tying up of psychic energy, become fixated  Oral stage: mouth, lips and tongue are the erogenous zones  Happens within the first 18 months of life  Phallic stage: erogenous zone becomes the penis  Oedipus complex: the child develops sexual attraction to the opposite sex parent  Boys develop castration anxiety; fearing that their fathers will discover these desires and cut their penises off  Girls develop penis envy; wishing they had a penis and feeling jealous that they do not  These feelings are repressed and result in an identification with the same sex parent, causing boys to develop masculine qualities and girls to develop feminine qualities  Never subsides completely  Latency stage: sexual desires abated, become interested in interacting with the same sex 4. Genital stage: erogenous zone returns to adult genitals, can perform sexually if not fixated on an earlier stage  How do we get at unconscious material o Dreams  Heavy emphasis on dreams  Freud believed that our dreams were symbolic of our unconscious desires, even though we may not realize it  Dreams provide the id with a stage for expression  Manifest content: content that the dreamer sees and remembers  Latent content: what is really being said through the dream  In dreams, unconscious thoughts are represented symbolically  Usually sexual symbols  House represents human body, kings and queens represent parents, bottles and boxes represent vaginas, where things such as hammers, pencils, sticks, etc. represent a penis  Freud believes psychoanalysts can determine what a dream may mean through these symbols o Projective tests: a test where the patient is shown ambiguous images and is asked to recount what they see  Responses are supposed to show insight into what is going on in their unconscious o Free association: allowing yourself to say whatever comes to mind, temporarily letting unconscious thoughts into awareness  Not very easy due to ego's efforts o Freudian slips  Misstatements that may symbolize unconscious desires that have momentarily slipped out o Hypnosis  Believes that hypnotism puts the ego in a deep trance allowing one to pass it into the unconscious mind  Not all patients respond to hypnotic suggestion o Accidents  Freud believes that most accidents are actually a manifestation of unconscious impulses and are not really accidents at all o Symbolic behavior  Pose no threat to the ego because they are not perceived as what they actually are  Behaviors that symbolize unconscious desires or impulses but are completely acceptable at face value  Application: Psychoanalysis o Freud also the first person to discover and advocate for a system of psychotherapy  Psychoanalysis  System of psychotherapy used to treat people with psychological disorders  Primary goal: to bring crucial unconscious material into consciousness where it can be examined rationally  Therapist and client work to help the ego regain control o Psychoanalysis can be a lengthy and difficult process, and is limited to those who can afford years of therapy as it is very expensive o Freud uses dream interpretation, free association, and hypnosis to get at this unconscious material  Therapist actively interprets the clients statements, behaviors, and dreams  Client must obtain an understanding of psychoanalytic theory before being able to appreciate the therapist's interpretations o Therapy progression:  Resistance: if the client is claiming that therapy isn't working, is missing appointments, or is resisting looking at certain material, this may mean that the client and therapist are getting at this crucial material  The ego is desperately trying to defend what it has spent so much energy suppressing  Transference: the displacement of emotions associated with people from the clients past onto the therapist  Usually the heart of their problem o Psychoanalysis always has been controversial, and still is today  Assessment: Projective Testing o Projective tests: a psychological assessment that present individuals with ambiguous stimuli such as inkblots or vague pictures which to they are asked to tell stories about, identify what they see, or talk about the picture  The responses are said to be projections from the unconscious mind  Therapist must interpret the responses of the client  Client has no idea what their responses mean, or what the material is testing  If the client was aware, the responses wouldn’t be coming from their unconscious o Types of Projective Tests:  Rorschach inkblot test: consists of ten cards with inkblots, sometimes in more than one color  Test takers are instructed to describe what they see; usually allowed to give more than one answer to a single card  Blots are literally just inkblots  Responses can be interpreted through many methods, but most rely on their personal insights  Thematic Apperception Test: formulated by Henry Murray; test takers are presented with ambiguous pictures and asked to tell a story about each one  Who the people are, what they are doing, why they are there, etc.  Responses provide clues into the persons personality  Many psychoanalysts use relatively objective scoring methods to interpret responses  Human Figure Drawing Test: patients are given a blank piece of paper and told to draw a picture for the psychologist; can be a person, a family, a tree; etc.  This test has many uses, such as an intelligence test for children and identifying important personality constructs  Also used to identify psychological problems in children  Psychologists usually see the resulting picture as a symbolic representation of the self  Evaluation: Projective Testing o Widely criticized; especially inkblot tests  Has been used to predict anything from intelligence to sexual orientation  Low indices of validity and reliability  People argue that the ink blot test is nothing more than a highly structured interview o Also widely advocated for  Main points:  One needs to separate good studies designed to test appropriate predictions from poor studies that attempt to tie test responses to any and all behaviors  Find evidence for the usefulness of the test when looking at good studies  More rigorous systems for coding responses have been developed and have proved more reliable  Establishing good validity for projective tests is much more difficult than for other studies o Despite controversy, Rorschach test and other projective tests are widely used  School psychologists use it to test for social and emotional adjustment in children  Psychologists use it in the field of law enforcement or law  May uncover information not easily obtained through other procedures  Many psychologists warn against over-interpreting responses to projective tests  Strengths and Weaknesses of Psychoanalytic Approach o Strengths  Freud's theory is the first comprehensive theory of personality and human behavior  Many built their theories off of Freud's, even if they completely disagreed with most of it  Set the direction for subsequent personality theory and research  First system of psychotherapy was developed  Free association, hypnosis, and dream interpretation still used today  Popularized important psychological concepts o Weaknesses / Criticisms  Many of Freud's ideas appeared in works that predated his  BUT he often cited earlier works when introducing ideas mentioned before and was the first one to develop a comprehensive theory form all of these ideas  Many of Freud's hypotheses cannot be tested and too much use of case studies  Case studies were biased as Freud's patients were usually not typical adults  Many thought that Freud neglected to pay attention to social and cultural influences on personality as well as influences from experiences after the first five years of life  Also thought he placed too much emphasis on disorders rather than everyday personality

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Chapter 2, Problem 2.23 is Solved
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Textbook: Fundamentals of Engineering Thermodynamics
Edition: 8
Author: Michael J. Moran
ISBN: 9781118412930

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The two major forces opposing the motion of a vehicle