Physics for Scientists and Engineers: Foundations and Connections
1st Edition
ISBN: 9781133939146
Author: Katz, Debora M.
Publisher: Cengage Learning
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Question
Chapter 21, Problem 7PQ
(a)
To determine
The energy equivalent of
(b)
To determine
The number of steps that the man has to take to work off the energy of the energy bar.
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The food calorie, equal to 4186 JJ, is a measure of how much energy is released when food is metabolized by the body. A certain brand of fruit-and-cereal bar contains 145 food calories per bar.
A.
If a 71.0 kgkg hiker eats one of these bars, how high a mountain must he climb to "work off" the calories, assuming that all the food energy goes only into increasing gravitational potential energy?
Express your answer in meters. H=____________m
B.
If, as is typical, only 25.0 %% of the food calories go into mechanical energy, what would be the answer to part A? (Note: In this and all other problems, we are assuming that 100%% of the food calories that are eaten are absorbed and used by the body. This is actually not true. A person's "metabolic efficiency" is the percentage of calories eaten that are actually used; the rest are eliminated by the body. Metabolic efficiency varies considerably from person to person.)
Express your answer in meters.
H=______________m
The winning time for the 2005 annual race up 86 floors of the Empire State Building was 10 min and 49 s. The winner’s mass was 60 kg.a. If each floor was 3.7 m high, what was the winner’s change in gravitational potential energy?b. If the efficiency in climbing stairs is 25%, what total energy did the winner expend during the race?c. How many food Calories did the winner “burn” in the race?d. Of those Calories, how many were converted to thermal energy?e. What was the winner’s metabolic power in watts during the race up the stairs?
A weightlifter works out at the gym each day. Part of her routine is to lie on her back and lift a 40 kg barbell straight up from chest height to full arm extension, a distance of 0.50 m.a. How much work does the weightlifter do to lift the barbell one time?b. If the weightlifter does 20 repetitions a day, what total energy does she expend on lifting, assuming a typical efficiency for energy use by the body.c. How many 400 Calorie donuts can she eat a day to supply that energy?
Chapter 21 Solutions
Physics for Scientists and Engineers: Foundations and Connections
Ch. 21.2 - Incorrect. Heat is not contained in Texas. The...Ch. 21.3 - In each situation listed, an objects temperature...Ch. 21.4 - Prob. 21.3CECh. 21.4 - Prob. 21.4CECh. 21.7 - Prob. 21.5CECh. 21.7 - Prob. 21.6CECh. 21.7 - Prob. 21.7CECh. 21.7 - Prob. 21.8CECh. 21.7 - Prob. 21.9CECh. 21 - Prob. 1PQ
Ch. 21 - Prob. 2PQCh. 21 - You extend an impromptu invitation to a friend for...Ch. 21 - Prob. 4PQCh. 21 - Prob. 5PQCh. 21 - Prob. 6PQCh. 21 - Prob. 7PQCh. 21 - Prob. 8PQCh. 21 - Prob. 9PQCh. 21 - Prob. 10PQCh. 21 - Prob. 11PQCh. 21 - Prob. 12PQCh. 21 - Prob. 13PQCh. 21 - Prob. 14PQCh. 21 - Prob. 15PQCh. 21 - Prob. 16PQCh. 21 - Prob. 17PQCh. 21 - Prob. 18PQCh. 21 - Prob. 19PQCh. 21 - From Table 21.1, the specific heat of milk is 3.93...Ch. 21 - Prob. 21PQCh. 21 - Prob. 22PQCh. 21 - An ideal gas is confined to a cylindrical...Ch. 21 - Prob. 24PQCh. 21 - You place frozen soup (T = 17C) in a microwave...Ch. 21 - A 25-g ice cube at 0.0C is heated. After it first...Ch. 21 - Prob. 27PQCh. 21 - Prob. 28PQCh. 21 - Prob. 29PQCh. 21 - Prob. 30PQCh. 21 - Consider the latent heat of fusion and the latent...Ch. 21 - Prob. 32PQCh. 21 - Prob. 33PQCh. 21 - A thermodynamic cycle is shown in Figure P21.34...Ch. 21 - Prob. 35PQCh. 21 - Figure P21.36 shows a cyclic thermodynamic process...Ch. 21 - Figure P21.37 shows a PV diagram for a gas that is...Ch. 21 - Prob. 38PQCh. 21 - Prob. 39PQCh. 21 - Prob. 40PQCh. 21 - Prob. 41PQCh. 21 - Prob. 42PQCh. 21 - Prob. 43PQCh. 21 - Prob. 44PQCh. 21 - Figure P21.45 shows a cyclic process ABCDA for...Ch. 21 - Prob. 46PQCh. 21 - Prob. 47PQCh. 21 - Prob. 48PQCh. 21 - Prob. 49PQCh. 21 - Prob. 50PQCh. 21 - Prob. 51PQCh. 21 - Prob. 52PQCh. 21 - Prob. 53PQCh. 21 - Prob. 54PQCh. 21 - Prob. 55PQCh. 21 - You extend an impromptu invitation to a friend for...Ch. 21 - Prob. 57PQCh. 21 - Prob. 58PQCh. 21 - A lake is covered with ice that is 2.0 cm thick....Ch. 21 - A concerned mother is dressing her child for play...Ch. 21 - Prob. 61PQCh. 21 - Prob. 62PQCh. 21 - Prob. 63PQCh. 21 - Prob. 64PQCh. 21 - Prob. 65PQCh. 21 - Prob. 66PQCh. 21 - Prob. 67PQCh. 21 - Prob. 68PQCh. 21 - Three 100.0-g ice cubes initially at 0C are added...Ch. 21 - Prob. 70PQCh. 21 - Prob. 71PQCh. 21 - Prob. 72PQCh. 21 - Prob. 73PQCh. 21 - Prob. 74PQCh. 21 - Prob. 75PQCh. 21 - Prob. 76PQCh. 21 - Prob. 77PQCh. 21 - Prob. 78PQCh. 21 - How much faster does a cup of tea cool by 1C when...Ch. 21 - The PV diagram in Figure P21.80 shows a set of...Ch. 21 - Prob. 81PQCh. 21 - Prob. 82PQCh. 21 - Prob. 83PQCh. 21 - Prob. 84PQCh. 21 - Prob. 85PQ
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.Similar questions
- (a) How long will the energy in a 1470kJ (350kcal) cup of yogurt last in a woman doing work at the rate of 150 W with an efficiency of 20.0% (such as in leisurely climbing stairs)? (b) Does the time found in part (a) imply that it is easy to consume more food energy than you can reasonably expect to work off with exercise?arrow_forward(a) How long can you play tennis on the 800 kJ (about 200 kcal) of energy in a candy bar? (b) Does this seem like a long time? Discuss why exercise is necessary but may not be sufficient to cause a person to lose weight.arrow_forwardA block of mass m = 200 g is released from rest at point along the horizontal diameter on the inside of hemispherical bowl of radius R = 30.0 cm, and the surface of the bowl is rough (Fig. P8.23). The blocks speed at point is 1.50 m/s. Figure P8.23 (a) What is its kinetic energy at point ? (b) How much mechanical energy is transformed into internal energy as the block moves from point to point ? (c) Is it possible to determine the coefficient of friction from these results in any simple manner? (d) Explain your answer to part (c).arrow_forward
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