Archimedes Principle states that the buoyant force on an object partially or fully submerged in a fluid is equal to the weight of the fluid that the object displaces. Thus, for an object of density 0 floating partly submerged in a fluid of density f, the buoyant force is given by F f t y 0 2h As yd dy, where t is the acceleration due to gravity and As yd is the area of a typical cross-section of the object (see the figure). The weight of the object is given by W 0 t y L2h 2h As yd dy (a) Show that the percentage of the volume of the object above the surface of the liquid is 100 f 2 0 f (b) The density of ice is 917 kgym3 and the density of seawater is 1030 kgym3 . What percentage of the volume of an iceberg is above water? (c) An ice cube floats in a glass filled to the brim with water. Does the water overflow when the ice melts? (d) A sphere of radius 0.4 m and having negligible weight is floating in a large freshwater lake. How much work is required to completely submerge the sphere? The density of the water is 1000 kgym3 .
Nutrition Notes Week 10 Functions of Protein in the Body A. Provides energy 1. Calorie restriction 2. Prolonged exercise B. However, cells use primarily fats and carbohydrates 1. Why It’s efﬁcient 2. It wastes calories to metabolize (break down) amino acids for energy C. Forms glucose 1. Amino acids can be converted into glucose 2. This happens when glucose is low 3. Through glycogenic amino acids 4. There are nonessential and essential amino acids 5. In starvation, muscle wasting and edema results from protein breakdown D. Contributes to satiety 1. Provides the highest feeling of satisfaction after eating 2. May contribute to collie control during weight loss The need for protein A. Only need it if you aren't growing (ie adults) B. Only need enough protein to replace what’s been lost daily C. This is often called protein breakdown/protein turnover Protein RDA A. 0.8 g of protein for every 1 kg of healthy body weight B. For an average person (150 lbs = 70 kg) this means 56 grams of protein C. This is about 10% of total calories D. Food and Nutrition Board want it closer to 35% E. In the U.S. the typical protein intake is about 100 grams for men and 65 grams for women F. Typical protein intake is greater than what is needed G. In the western diet, 70% of dietary protein comes from animal sources H. Water packed tuna is the most nutrient-dense source of protein I. Top contributors of protein in the American diet include beef, poultry, milk, white bread, and cheese J. The problem with so many animal sources is that they tend to be low in ﬁber, some vitamins, phytochemicals, and high in saturated fat and cholesterol K. Red meat is very strongly linked with colon cancer, especially in any processed form L. High protein diet is stressful on the kidneys M. Some studies show that high protein diets are associated with calcium losses in urine Alternatives to the typical high-protein diet A. Vegetarian- no meat at all B. Semi-vegetarian- no meat typically but occasionally consume ﬁsh and poultry or meats infrequently C. Vegan- no animal products, which can cause a lot of health issues 1. Need complimentary proteins 2. Nutrient deﬁciency concerns, such as iron, vitamin B12, zinc, calcium (dairy), omega-3 fatty acids (ﬁsh/ﬁsh oil) D. Animal proteins are considered to be complete proteins/high quality, because they contain all essential amino acids in abundance E. Plant proteins tend to be incomplete proteins/low quality, because they are low in one or more of the essential amino acids F. Plant sources of proteins 1. Nuts 2. Seeds 3. Legumes G. With a vegetarian diet, there are speciﬁc protein requirements 1. Grains and nuts are low in the amino acid lysine 2. Vegetables and legumes are low in methionine 3. Complementary proteins combine two or more of the following to compensate for deﬁciencies in essential amino acids needed for each proteins Complete protein in plants A. Quinoa- grain like B. Amaranth- seeds are ground into ﬂour and the leafy greens rival swinish and kale for nutrients C. Soybeans- made up of 47% protein D. Buckwheat- not wheat, but actually relayed to rhubarb; the grain is ground into ﬂour Protein consumption complications A. Gluten sensitivity B. Allergies related to peanuts, tree nuts, shellﬁsh, eggs, milk, soy, wheat, ﬁsh C. The immune system mistakes food protein for harmful invaders D. 8 foods account for 90% of food-related allergies E. Reactions range from intolerance to fatal allergic reactions Protein-Calorie Malnutrition A. In the developed world, diet is typically rich in protein B. In the developing world, protein deﬁciency is an issue, which is important in diet planning C. It is rare to see protein deﬁciency in developed countries, but it is seen in certain populations D. In developing countries, it can stunt growth and increase the risk of infection E. Protein-Energy Malnutrition called marasmus which is apparent in starvation or where there is insufﬁcient protein and calories F.Kwashiorkor is marginal amount of calories but severe protein deﬁcit G. These diseases are commonly found in Africa H. In the U.S., it can be found in hospital patients, long-rem care residents, community- dwelling adults, dialysis patients (In every one of these cases, the victims are all older adults over 65 years old) Megadoses of Vitamins A. Beyond estimates of needs B. Not in a balanced diet C. 2-10x human needs D. Usually through supplements E. Increased risk for toxicity symptoms F. Proven useful in treating several nondiﬁciency diseases G. Oversupplementation can leads to vitamin levels building up over time H. Vitamins can be stored within the body I. Fat soluble vitamins (especially vitamin A) have the potential to reach toxic levels Vitamin Preservation A. The riper the food, the more vitamins B. Vitamins lost from time picked to consumed C. Best to eat as soon as possible after harvest D. Water soluble vitamins destroyed by improper storage or excessive cooking E. Heat, light, air, cooking in water, alkalinity F. How to preserve vitamins in foods 1. Freezing- best method 2. Blanching- destroys enzymes that degrade the vitamins Two Classes of Vitamins A. Fat soluble vitamins- A, D, E, K 1. absorbed in chylomicron 2. Stored in liver and fatty tissue 3. Not readily excreted B. Water- soluble vitamins- C and B vitamins 1. Absorbed through the capillaries 2. In general, not stored to a great degree 3. Excess excreted in urine Vitamin A (Retinoids) and Carotenoids A. Vitamin A (preformed) 1. Retinol 2. Retinal 3. Retinoid acid 4. Note- exist only in animal products and in supplements B. Carotenoids 1. Contained in plant pigments 2. Phytochemicals- polyphenols 3. Principle pigments for red, orange, yellow and green colored fruits/vegetables 4. Some are precursors to vitamin A, such as provitamin A 6. Beta-carotene- carotenoid that can be sufﬁciently absorbed and converted into retinol Functions of Vitamin A and Carotenoids A. Health of epitheal cells and immune function 1. Maintains health of epithelial cells that line internal/exterbak surfaces 2. Lungs, intestines, stomach, vagine, urinary tract, bladder, eyes and skin 3. Healthy epithet tissues serve as important barriers to infection B. Vision 1. Night blindness- vitamin A deﬁciency disorder that results in loss of ability to see under low-light conditions 2. Vitamin A important for light-dark vision and color vision 3. Retina consist of rods and cones 4. Rods detect black and white, night vision 5. Cones responsible for color vision 6. Lutein and zeaxanthin in high concentrations in retina a. Found in leafy green vegetables b. Help prevent macular degeneration c. Food sources may help decrease risk of calories C. Cardiovascular Disease 1. Carotenoids may decrease rise by preventing oxidation of LDL 2. Recommendations to consume 5 servings a day of fruit and vegetables