BIO Doughnuts: Breakfast of Champions! Atypical doughnut contains 2.0 g of protein, 17.0 g of carbohydrates, and 7.0 g of fat. Average food energy values are 4.0 kcal/g for protein and carbohydrates and 9.0 kcal/g for fat. (a) During heavy exercise, an average person uses energy at a rate of 510 kcal/h. How long would you have to exercise to “work off” one doughnut? (b) If the energy in the doughnut could somehow be converted into the kinetic energy of your body as a whole, how fast could you move after eating the doughnut? Take your mass to be 60 kg, and express your answer in m/s and in km/h.
BIO Doughnuts: Breakfast of Champions! Atypical doughnut contains 2.0 g of protein, 17.0 g of carbohydrates, and 7.0 g of fat. Average food energy values are 4.0 kcal/g for protein and carbohydrates and 9.0 kcal/g for fat. (a) During heavy exercise, an average person uses energy at a rate of 510 kcal/h. How long would you have to exercise to “work off” one doughnut? (b) If the energy in the doughnut could somehow be converted into the kinetic energy of your body as a whole, how fast could you move after eating the doughnut? Take your mass to be 60 kg, and express your answer in m/s and in km/h.
BIO Doughnuts: Breakfast of Champions! Atypical doughnut contains 2.0 g of protein, 17.0 g of carbohydrates, and 7.0 g of fat. Average food energy values are 4.0 kcal/g for protein and carbohydrates and 9.0 kcal/g for fat. (a) During heavy exercise, an average person uses energy at a rate of 510 kcal/h. How long would you have to exercise to “work off” one doughnut? (b) If the energy in the doughnut could somehow be converted into the kinetic energy of your body as a whole, how fast could you move after eating the doughnut? Take your mass to be 60 kg, and express your answer in m/s and in km/h.
A food calorie is a unit of energy such that 1 food calorie = 4184 J. This means that a person that burns energy with a power of 4184 W would burn one food calorie every second. A more typical human power rate is 90 W (called the basal metabolic rate). At this rate, how many calories are burned per second (or alternatively, how many seconds does it take to burn 1 calorie)?
The total consumption of electrical energy in the United States is about 1.0 1019 joules per year. What is the average rate of electrical energy consumption in watts? If the population of the United States is 300 million, what is the average rate of electrical energy consumption per person? The sun transfers energy to the earth by radiation at a rate of approximately 1.0 kW per square meter of surface. If this energy could be collected and converted to electrical energy with 40 % efficiency, how great an area (in square kilometers) would be required to collect the electrical energy used by the United States?
A student evaluates a weight loss program by calculating the number of times she would need to climb a 10.0 m high flight of steps in order to lose one pound (0.45 kg) of fat. Metabolizing
1.00 kg of fat can release 3.77 x 10'J of chemical energy and the body can convert about 21.2% of this into mechanical energy (the rest goes into internal energy.)
HINT
(a) How much mechanical energy (in J) can the body produce from 0.450 kg of fat?
(b) How many trips up the flight of steps are required for the 52.0 kg student to lose 0.450 kg of fat? Ignore the relatively small amount of energy required to return down the stairs.
trips
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University Physics with Modern Physics Plus Mastering Physics with eText -- Access Card Package (14th Edition)
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