Unit 1 Tutorial

CC2404 Applied Physics and Instrumentation in Health Care Supplementary Problems Unit 1 Measurement and units 1. A space shuttle orbits the Earth at altitude of 280 km. What is the altitude in (a) miles and (b) mm? (Ans. a. 173.9 mi, b. 2.8 x108mm) 2. The Earth is approximately a sphere of radius 6.37x106 m. (a) What is its circumference in kilometers? (b) What is its surface area in square kilometers? (c) What is its volume in cubic kilometers? (Ans. a. 4.0 x 104km, b. 5.1 x 10 8km2, c. 1.1 x 1012km3)) 3. Enrico Fermi once pointed out that a standard lecture period is close to 1 microcentury. How long is a microcentury in minutes, and is it a long or short lecture for you? (Ans. 53 min.) 4. A person on diet might lose 1.3 kg of fat per week. Assuming to lose 100 g of fat is equal to consume 250 calories, express the energy loss rate in calories per day. (Ans. 464 cal) Energy 5. (P.P Urone 2001, Problem 6.10) (a) How fast must a 3000 kg elephant move to have the same kinetic energy as a 65.0 kg sprinter running at 10.0 m/s? (b) Discuss how the larger energies needed for the movement of larger animals would relate to metabolic rates. (Ans. Velephant=1.47m/s) 6. (P.P Urone 2001, Problem 6.50) (a) What is the efficiency of an out-of-condition professor who does 1.10 x 105 J of useful energy while metabolizing 500 kcal of food energy? (b) How many food calories would a well-conditioned athlete metabolize in giving the same energy with an efficiency of 20%? (given 1 cal = 4.186 J) (Ans. a. 5.3%, b. 131 kcal) Buoyant force 7. (P.P Urone 2001, Problem 10.44) A rock with a mass of 540 g in air is found to have an apparent mass of 342 g when submerged in water. (a) What mass of water is displaced? (b) What is the volume of the rock? (c) What is its average density? (density of water 1 g/ cm3). (Ans. a. 198g, b. 198 cm3,c. 2.73g/cm3). 8. (P.P Urone 2001, Problem 10.47) Some fish have a density slightly less than that of water and must exert a force (swim) to stay submerged. What force must a 85.0 kg fish exert to stay submerged in salt water if its body density is 1015 kg/m3? (density of salt water 1025 kg/m3). (Ans. 8N)