A man attempts to support a stack of books horizontally by applying a compressive force of F = 120 N to the ends of the stack with his hands. If each book has a mass of 0.95 kg, determine the greatest number of books that can be supported in the stack. The coefficient of static friction between his hands and a book is (ms)h = 0.6 and between any two books (ms)b = 0.4. F 120 N F 120 N Prob. 821
NUTRITION POWERPOINT 1 ● some people have food security for a long period of time and then they lose their job and become food insecure ● poor, homeless people, and female headed households with young children living in inner cities are at highest risk for food insecurity ● nutrition is an interdisciplinary science ○ chemical sciences ○ social sciences ○ behavioral sciences ○ biological sciences ○ food sciences ● food terrorism ○ botulism toxin ■ single most poisonous substance known ■ boil at 160 degrees fahrenheit or greater for 15 minutes to destroy ○ ricin ■ found in seed of castor plant ■ deadly if ingested ○ radioactive particles ○ microorganisms ■ salmonella ■ E. coli ● antioxidant: stops/prevents cells from being destroyed by ozone layer, oxygen, pollution, and smoke ● oxidation: causes damages to skin cells ○ worsens aging ○ antioxidants prevents cells from breaking down ■ 12-13 hour lifespan and then the body gets rid of them ● macronutrients ○ carbs ○ proteins ○ fats ● micronutrients ○ vitamins ○ minerals ○ water ○ phytochemicals ○ antioxidants ● carbs: primary source of energy ○ simple sugars ■ most basic carb ■ table sugar, milk sugar, blood sugar ■ 4 calories per gram ○ starches ■ complex carbs ■ long chains of simple sugars ■ 4 calories per gram ○ dietary fiber ■ complex carbs from plant cell wall ■ unable to digest… provides zero calories ● proteins: composed of 20 amino acids ○ 9 must be acquired from diet ○ 4 calories per gram ● fats ○ saturated = animal products ■ 9 calories per gram ■ can increase cholesterol levels ○ unsaturated = plant products, nuts, fish ■ some must be acquired from diet ■ 9 calories per gram ■ helps to decrease risk of heart disease ○ trans fat: good fats that have been transformed into bad fats ■ molecule of a trans fat will stick to your arteries like glue ■ anything processed or fried ○ cholesterol: only found in animals ■ provides zero calories ■ high levels increase risk of heart attack or stroke ● vitamins: found in food ○ 13 kinds ○ 0 calories ● minerals: found in food ○ 15 kinds ○ 0 calories ○ ash that remains ● water : essential for life ○ 11 to 15 cups daily from food and fluids ● vitamins, minerals, and water are needed to convert carbs, fats, and protein into usable energy and aid in building and maintaining muscles, blood components, and blood ● phytochemicals : provide plants with color ○ flavor ○ protects plants from insects and disease ● non essential nutrients: cholesterol and certain amino acids ● multivitamins are not the same as eating vegetables ● sulfur containing phytochemicals helps to prevent certain cancers ○ ex. brussel sprouts helps to reduce the risk ● we need omega 3 ○ fish ○ used with antidepressants to help with mood disorder ● with persistent drug use, sometimes the body has completely lost the ability to absorb nutrients ● males require more calories than females ● diet varies from person to person and day by day ○ gender ○ age ○ growth status ○ body size ○ genetic traits ● in addition to certain conditions… ○ pregnancy ○ breastfeeding ○ illness ○ drug use ○ exposure to environmental contaminants ● growth and health take place within the cell and the fluid surrounding them ● body consists of over 100 trillion cells ● functions are maintained by the nutrients it receives ● problems arise when a cell’s need for nutrients differs from the available supply ● cells need to live in a utopia ● if deficient or toxic levels… ○ organ failure ○ cells produce proteins in abnormal forms ● health problems related to nutrition originate within the cells ● poor nutrition can result from both inadequate and excessive levels of nutrient intake ● for every nutrient there is a range of optimal intake for cell functioning ○ either side of the range is associated with… ■ behavioral/cognitive disabilities ■ physical ● humans have adaptive mechanisms for managing fluctuations in nutrient intake ● some nutrients are stored for later ○ glucose ○ fat ○ iron ○ calcium ○ Vitamin A ○ B12 ● the body has a low storage capacity for some nutrients ○ vitamin c ○ water ● GI tract can increase or decrease absorption based on need ○ iron and calcium ● malnutrition ○ lack or excess of nutrients and calories ■ vitamin A toxicity ■ obesity ■ vitamin c ■ underweight ● diseases that interfere with the body’s ability to use the nutrients consumed ○ diarrhea ○ alcoholism ○ cancer ○ bleeding ulcers ○ HIV/AIDS ● genetic traits ○ cholesterol ○ chronic disease ■ diabetes ■ heart disease ● some people are at a higher risk of becoming inadequately nourished than others ○ women who are pregnant ○ women who are breastfeeding ○ infants ○ growing children ○ elderly ○ the ill ○ people recovering from illness ○ food shortages, natural diseases, war ○ poverty ● heart disease ○ high saturated fats ● hypertension ○ high consumption of salty foods ● cancer ○ low fruits and veggies ● osteoporosis ○ low calcium ● adequacy, variety, and balance are key characteristics of a healthy diet ● many different foods together provide optimal functioning of the body ● no one food contains all the nutrients we need ○ except breast milk for infants ● nutrient-dense food: contains relatively high amounts of nutrients compared to their calorie value ○ good for you foods ● thing to remember: quality, quantity, frequency ● there are no good or bad foods, only healthy and unhealthy foods