College Physics (10th Edition)
10th Edition
ISBN: 9780321902788
Author: Hugh D. Young, Philip W. Adams, Raymond Joseph Chastain
Publisher: PEARSON
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Chapter 7, Problem 32P
Food calories. The food calorie, equal to 4186 J, 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 140 food calories per bar. (a) If a 65 kg 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? (b) If, as is typical, only 20% 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 “
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The food calorie, equal to 4186 J, is a measure of how much energy is released when food is metabolized by the body. A Milo Bar contains 180 food calories per bar. (a) If a 70-kg hiker eats one Milo Bar, 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? (b) If, as is typical, only 20% of the food calories go into mechanical energy, what would be the answer to part (a)? (NOTE: In this problem, we assume 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.)
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 box of a well-known breakfast cereal states that one ounce of the cereal contains 103 Calories (1 food Calorie = 4186 J). If 1.58% of this energy could be converted by a weight lifter's body into work done in lifting a barbell, what is the weight of the heaviest barbell that could be lifted a distance of 1.63 m?
Chapter 7 Solutions
College Physics (10th Edition)
Ch. 7 - A box is pushed across a rough horizontal surface...Ch. 7 - Can the total work done on an object during a...Ch. 7 - True or false? If hydrogen molecules and oxygen...Ch. 7 - An elevator is hoisted by its cables at constant...Ch. 7 - A satellite moves in a circular orbit at a...Ch. 7 - If a projectile is fired upward at various angles...Ch. 7 - A block is initially traveling at a speed vc at...Ch. 7 - An advertisment for a portable electrical a...Ch. 7 - A child can slide down any of the three slides...Ch. 7 - Hydroelectric energy comes from gravity pulling...
Ch. 7 - Does the kinetic energy of a car change more when...Ch. 7 - When you jump from the ground into the air, where...Ch. 7 - Two unequal masses are connected by a massless...Ch. 7 - On your electric bill, you are charged for...Ch. 7 - In Figure 7.42, two blocks with masses mA and mB,...Ch. 7 - A car is initially traveling at a speed of v0....Ch. 7 - A spiral spring is compressed so as to add U units...Ch. 7 - You slam on the brakes of your car in a panic and...Ch. 7 - Consider two frictionless inclined planes with the...Ch. 7 - A brick is dropped from the top of a building...Ch. 7 - Prob. 5MCPCh. 7 - Two identical objects are pressed against two...Ch. 7 - For each of two objects with different masses, the...Ch. 7 - Two objects with unequal masses are released from...Ch. 7 - Spring #1 has a force constant of k, and spring #2...Ch. 7 - Two balls having different masses reach the same...Ch. 7 - A fisherman reels in 12.0 m of line while landing...Ch. 7 - A tennis player hits a 58.0 g tennis ball so that...Ch. 7 - A boat with a horizontal tow rope pulls a water...Ch. 7 - A constant horizontal pull of 8.50 N drags a box...Ch. 7 - A rope is tied to a box and used to pull the box...Ch. 7 - A 128.0 N carton is pulled up a frictionless...Ch. 7 - A factory worker moves a 30.0 kg crate a distance...Ch. 7 - An 8.00 kg package in a mail-sorting room slides...Ch. 7 - A tow truck pulls a car 5.00 km along a horizontal...Ch. 7 - A 60 kg woman steps onto an up-going escalator,...Ch. 7 - A bullet is fired into a large stationary absorber...Ch. 7 - Animal energy. Adult cheetahs, the fastest of the...Ch. 7 - A 0.145 kg baseball leaves a pitchers hand at a...Ch. 7 - A 1.50 kg book is sliding along a rough horizontal...Ch. 7 - Stopping distance of a car. The driver of an 1800...Ch. 7 - You throw a 20 N rock into the air from ground...Ch. 7 - Fleas are agile, wingless insects that feed on the...Ch. 7 - A 61 kg skier on level snow coasts 184 m to a stop...Ch. 7 - A block of ice with mass 2.00 kg slides 0.750 m...Ch. 7 - To stretch a certain spring by 2.5 cm from its...Ch. 7 - A spring is 17.0 cm long when it is lying on a...Ch. 7 - A spring with spring constant 100 N/m and...Ch. 7 - The graph in Figure 7.440 shows the magnitude of...Ch. 7 - A 575 N woman climbs a staircase that rises at 53...Ch. 7 - How high can we jump? The maximum height a typical...Ch. 7 - A 72.0 kg swimmer jumps into the old swimming hole...Ch. 7 - A 2.50 kg mass is pushed against a horizontal...Ch. 7 - A force of magnitude 800.0 N stretches a certain...Ch. 7 - Tendons. Tendons are strong elastic fibers that...Ch. 7 - A certain spring stores 10.0 J of potential energy...Ch. 7 - A 0.5 kg ball is thrown up into the air with an...Ch. 7 - Food calories. The food calorie, equal to 4186 J,...Ch. 7 - A good workout. You overindulged in a delicious...Ch. 7 - An exercise program. A 75 kg person is put on an...Ch. 7 - Tall Pacific Coast redwood trees (Sequoia...Ch. 7 - The total height of Yosemite Falls is 2425 ft. (a)...Ch. 7 - The speed of hailstones. Although the altitude may...Ch. 7 - Prob. 38PCh. 7 - Volcanoes on lo. lo, a satellite of Jupiter, is...Ch. 7 - Human energy vs. insect energy. For its size, the...Ch. 7 - A 25 kg child plays on a swing having support...Ch. 7 - A slingshot obeying Hookes law is used to launch...Ch. 7 - A spring with spring constant k is anchored to the...Ch. 7 - A 1.5 kg box moves back and forth on a horizontal...Ch. 7 - A 12.0 N package of whole wheat flour is suddenly...Ch. 7 - A spring of negligible mass has force constant k =...Ch. 7 - A 1.50 kg brick is sliding along on a rough...Ch. 7 - A fun-loving 11.4 kg otter slides up a hill and...Ch. 7 - A 12.0 g plastic ball is dropped from a height of...Ch. 7 - You are rearranging the furniture in your living...Ch. 7 - While a roofer is working on a roof that slants at...Ch. 7 - A block with mass 0.50 kg is forced against a...Ch. 7 - A loaded 375 kg toboggan is traveling on smooth...Ch. 7 - A 62.0 kg skier is moving at 6.50 m/s on a...Ch. 7 - Suppose you were to drop a 14 lb bowling ball from...Ch. 7 - The engine of a motorboat delivers 30.0 kW to the...Ch. 7 - Prob. 57PCh. 7 - A tandem (two-person) bicycle team must overcome a...Ch. 7 - An elevator has mass 600 kg, not including...Ch. 7 - U.S. power use. The total consumption of...Ch. 7 - Solar energy. The sun transfers energy to the...Ch. 7 - A 20.0 kg box is pulled along a rough horizontal...Ch. 7 - A typical flying insect applies an average force...Ch. 7 - When its 75 kW (100 hp) engine is generating full...Ch. 7 - The power of the human heart. The human heart is a...Ch. 7 - At the site of a wind farm in North Dakota, the...Ch. 7 - A physics student measures the energy stored in a...Ch. 7 - Human terminal velocity. By landing properly and...Ch. 7 - A wooden rod of negligible mass and length 80.0 cm...Ch. 7 - Ski jump ramp. You are designing a ski jump ramp...Ch. 7 - Rescue. Your friend (mass 65.0 kg) is standing on...Ch. 7 - On an essentially frictionless horizontal...Ch. 7 - Pendulum. A small 0.12 kg metal ball is tied to a...Ch. 7 - A pump is required to lift 750 liters of water per...Ch. 7 - A 350 kg roller coaster starts from rest at point...Ch. 7 - In action movies there are often chase scenes in...Ch. 7 - In creating his definition of horsepower, James...Ch. 7 - All birds, independent of their size, must...Ch. 7 - A 250 g object on a frictionless, horizontal lab...Ch. 7 - Bungee jump. A bungee cord is 30.0 m long and,...Ch. 7 - Riding a loop-the-loop. A car in an amusement park...Ch. 7 - A 2.0 kg piece of wood slides on the surface shown...Ch. 7 - A 68 kg skier approaches the foot of a hill with a...Ch. 7 - Energy requirements of the body. A 70 kg human...Ch. 7 - The aircraft carrier USS George Washington has...Ch. 7 - A ball is thrown upward with an initial velocity...Ch. 7 - Automotive power. A truck engine transmits 28.0 kW...Ch. 7 - Prob. 88PPCh. 7 - Prob. 89PPCh. 7 - How many times greater is the kinetic energy of...Ch. 7 - During the calibration process, the cantilever is...Ch. 7 - A segment of DNA is put in place and stretched....Ch. 7 - Based on Figure 7.52, how much elastic potential...Ch. 7 - The stage moves at a constant speed while...
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