A disk having moment of inertia 100 kg ? m2 is free to rotate without friction, starting from rest, about a fixed axis through its center. A tangential force whose magnitude can range from F 5 0 to F 5 50.0 N can be applied at any distance ranging from R 5 0 to R 5 3.00 m from the axis of rotation. (a) Find a pair of values of F and R that cause the disk to complete 2.00 rev in 10.0 s. (b) Is your answer for part (a) a unique answer? How many answers exist?
Need to Know for Chapter 13 1. Emerging Adulthood: - Three criteria that most people use for adulthood: a. Accepting responsibility for oneself b. Making independent decisions c. Becoming financially independent - EMERGING ADULTHOOD – young adults can figure out who they are and what they want to be - Sexual maturity occurs during adolescence - Cognitive maturity usually takes longer - People may be considered adults when they are self- supporting or have chosen a career, have married or formed a significant romantic partnership, or have started a family. - Psychological maturity may depend on such achievements as discovering one’s identity, becoming independent or parents, developing a system of values, and forming relationships. - For most laypeople, three criteria define adulthood: a. Accepting responsibility for oneself b. Making independent decisions c. Becoming financially independent - Emerging adulthood is a time during which young people are no longer adolescents but have not yet settled into adult roles. 2. Sleep Deprivation: - In the 20’s and 30’s people are usually very busy with their lives. They tend to go without adequate sleep - Sleep deprivation affects not only physical health, but cognitive, emotional and social functioning as well. - In a poll by the National Sleep Foundation, respondents said they were more likely to make mistakes, become impatient or aggravated when waiting, or get upset with their children or others when they had not had enough sleep the night before. - Lack of sleep tends to impair verbal learning, some aspects of memory, high-level decision making, and speech articulation, and increases distractibility. - Chronic sleep deprivation can seriously worsen cognitive performance and has been linked to depression. - Performance impairments related to even partial sleep deprivation have been shown to be similar to those found after drinking alcohol. 3. Sleep and Motor Skills: - Adequate sleep improves learning of complex motor skills and consolidates previous learning. - A short nap can prevent a burnout - BURNOUT – oversaturation of the brain’s perceptual processing systems 4. Alcoholism: - In the United States, advertising associated liquor, beer, and win with the good life and being grown-up - Alcohol use peaks in emerging adulthood - College students tend to drink more frequently and more heavily than their non-collegiate peers. - In 2007, nearly 64% of full-time college students ages 18- 20 had used alcohol in the past month. - Although light to moderate alcohol consumption seems to reduce the risk of fatal heart disease and stroke, and also of dementia later in life, heavy drinking over the years may lead to cirrhosis of the lives, other gastrointestinal disorders, pancreatic disease, certain cancers, heart failure, stroke, damage to the nervous system, psychoses, and other medical problems - RISKY DRINKING – consuming more than 14 drinks a week or 4 drinks on any single day for men and more than 7 drinks a week or 3 drinks on any single day for women. - Approximately 3 out of 10 people are risky drinkers - Race and ethnicity can affect drinking patterns. - The group reporting the highest consumption of alcohol is Native Americans, followed by whites, and the lowest levels of use are reported by Central Americans, African Americans, and Asian Americans. 5. Health Among Racial/Ethnic Groups: - Because many minorities in the United States have a lower SES, their health issues stem from that rather than from minority status. - 39% of African American men and 43% of African American women aged 20 years and older suffer from high blood pressure. - African Americans are more likely to be diagnosed with diabetes and more likely to die from it as well. - African Americans are about twice as likely as white people to die in young adulthood, in part because young African American men are far more likely to be victims of homicide. - African Americans metabolize more nicotine in the blood, face higher risks of lung cancer, and have more trouble breaking the habit than white people; even though they smoke less than white people. - Racial/ethnic minorities tend to receive lower-quality health care than white people do, even when insurance status, income, age, and severity of conditions are similar. 6. Sense of Well-Being and Stress: - Social relationships seem to be vital to health and well- being. - SOCIAL INTEGRATION – active engagement in a broad range of social relationships, activities, and roles. - Social networks can influence emotional well-being as well as participation in healthful behavior, such as exercising, eating nutritiously, and refraining from substance use. - Social integration has repeatedly been associated with lower mortality rates. - People with wide social networks and multiple social roles are more likely to survive heart attacks and less likely to be anxious or depressed. - The beneficial effects of social integration may in part be due to the decreases in stress levels that strong social ties can engender. - SOCIAL SUPPORT – material, informational, and psychological resources derived from the social network, on which a person can rely for help in coping with stress. - In highly stressful situations, people who are in touch with others may be more likely to eat and sleep sensibly, get enough exercise, and avoid substance abuse, and are less likely to be distressed, anxious, or depressed or even to die. 7. Depression/Depressive Episode: - Adolescence and emerging adulthood appear to be sensitive periods for the onset of depressive disorders. - Between ages 15 and 22, the incidence of depression increases gradually. - DEPRESSIVE MOOD – an extended period of sadness. - DEPRESSIVE SYNDROME - an extended period of sadness along with a variety of other symptoms such as crying and feelings of worthlessness or hopelessness. - MAJOR DEPRESSIVE DISORDER – a clinical diagnosis with a specific set of symptoms and generally requires medical intervention. - People who are diagnosed with major depressive disorder often have depressed or irritable moods for most of the day, every day, show reduced interest in and enjoyment of previously pleasurable activities, often either gain or lose significant amount of weight, have difficulties sleeping too little or too much, and often show a variety of cognitive biases and maladaptive recurrent thoughts. - Generally, young women are more likely to suffer from a major depressive episode, and this difference in prevalence becomes particularly acute after the onset of puberty. 8. Sexual Behavior and Attitudes: - Attitudes: a. Today, almost all U.S. adults have had sexual relations before marriage b. Emerging adults tend to have more sexual partners than in older age groups c. Casual sex common on college campuses d. Sexual identity tends to be clear by emerging adulthood - By emerging adulthood, most lesbian, gay, bisexual, and transgender persons are clear about their sexual identity. - Sexual assaults on women are also a problem for college students. - STI’s: a. Half of all new STI cases are in 18-25 age groups b. Highest rates are among teens and young adults c. Number of people living with HIV has risen worldwide 9. Infertility: - An estimated 7% of U.S. couples experience infertility - INFERTILITY – inability to conceive a baby after 12 months of trying - Women’s fertility begins to decline in their late 20’s, with substantial decreases during their 30’s. - By their 40’s, many women are not able to become pregnant without the use of artificial reproduction technologies. - Most common cause of infertility in males is low sperm count. - In women, the most common causes are a. Failure to produce ova or abnormal ova b. Mucus in the cervix c. Endometriosis - Assisted Reproduction Technology: a. In vitro fertilization b. In vitro maturation c. Artificial insemination d. Ovum transfer e. Surrogate motherhood f. Legal and ethical issues 10. Piaget’s Thinking in Adulthood: - Piaget believed that the pinnacle of cognitive development was formal operations thought - In this stage, adults were presumed to be capable of fully abstract thought and formal hypothesis testing. - REFLECTIVE THINKING – active, persistent, and careful consideration of information or beliefs in the light of the evidence that supports them and the conclusions to which they lead. - Reflective thinkers continually question supposed facts, draw inferences, and make connections. (frequently engage in critical thinking) - Reflective thinking emerges between 20 and 25 years - Cortical regions with enriched myelination - POSTFORMAL THOUGHT – the ability to deal with inconsistency, contradiction, and compromise. - Post-formal thought draws on intuition, emotion, and logic. - Components of post-formal thought: shifting gears, problem definition, process-product shift, pragmatism, multiple solutions, awareness of paradox, self-referential thought. 11. Piaget vs Schaie’s Models: - Schaie: Life Span Model of Cognitive Development: 7 stage model: a. Acquisitive Stage: (childhood and adolescence) children and adolescents acquire information and skills mainly for their own sake or as preparation for participation in society. (Example: a child might read about dinosaurs out of pure interest in the topic) b. Achieving Stage: (Late teens or early 20’s to early 30’s) Young adults no longer acquire knowledge merely for its own sake; they use what they know to pursue goals, such as career and family. (Example: a young adult might take a college class as preparation for a career in a particular area.) c. Responsible Stage: (Late 30’s to early 60’s) Middle- aged people use their minds to solve practical problems associated with responsibilities to others, such as family members or employees. (Example: an adult might figure out a more efficient way to complete a task at work) d. Executive Stage: (30’s or 40’s through middle age) People in the executive stage are responsible for societal systems or social movements. They deal with complex relationships on multiple levels. (Example: an adult might mediate a disagreement between two coworkers so the office runs more smoothly) e. Reorganizational Stage: (end of middle age, beginning of late adulthood) People who enter retirement reorganize their lives and intellectual energies around meaningful pursuits that take the place of paid work. (Example: a retired adult might decide to volunteer at a local botanical garden) f. Re-integrative Stage: (late adulthood) older adults may be experiencing biological and cognitive changes and tend to be more selective about what tasks they expend effort on. They focus on the purpose of what they do and concentrate on tasks that have the most meaning for them. (Example: a person feeling the effects of age on her joints might decide to take a daily walk rather than a run for health) g. Legacy-Creating Stage: (advanced old age) Near the end of life, once reintegration has been completed (or along with it), older people may creating instructions for the disposition of prized possessions, make funeral arrangements, provide oral histories, or write their life stories as a legacy for their loved ones. (Example: an older adult might complete an advance directive and distribute that to his children.) - This approach suggests that intelligence looks different depending on the stage of life of the person. 12. Kohlberg’s Moral Development: - Moral development of children and adolescents is closely tied to cognitive maturation. - Personal experiences can affect the likelihood of engaging in certain types of moral reasoning. - When young people encounter values that conflict with their own and when they are responsible for the welfare of others, their development of moral reasoning abilities increases. - Experience may lead adults to reevaluate their criteria for what is right and wrong. 13. Male vs Female High School Graduates: - Between 1975 and 2011, the proportion of U.S. high school graduates who went straight into a 2 or 4 year college grew from about half to more than two thirds. - Women generally do better than men in high school math and science courses, they tend to score lower on standardized college and graduate school entrance tests. - Approximately 72% of bachelor’s degrees are earned by white students. - Minority participation, has risen at all levels. - In 2006, women made up 66% if U.S. undergraduate students and in 2010, slightly over 57% of those earning bachelor’s degrees. - Women are more likely than men to enroll in graduate school and earn master’s degrees 14. College Transition: - U.S. college enrollment is at a record high - 38% of all 18-24 year olds - Key factors to adjustment: a. Financial support b. Emotional support c. Adaptability d. High aptitude and problem-solving skills e. Engaged in studies and social environment - Cognitive growth in college: a. Thinking progresses from rigidity to flexibility to freely chosen commitments b. Ultimately, commitment within relativism - Only 1 out of 4 who start college has a degree within five years - Completing college depends on: a. Motivation and aptitude b. Ability to work independently c. Social integration and support d. Fit between school and student