Connect with LearnSmart for Krauskopf: The Physical Universe, 16e
16th Edition
ISBN: 9781259663895
Author: KRAUSKOPF, Konrad B.
Publisher: Mcgraw-hill Higher Education (us)
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Chapter 3, Problem 39E
In an effort to lose weight, a person runs 5 km per day at a speed of 4 m/s. While running, the person’s body processes consume energy at a rate of 1.4 kW. Fat has an energy content of about 40 kJ/g. How many grams of fat are
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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)?
Under normal conditions the human heart converts about 12.7 J of chemical energy per second into 1.27 W of mechanical power as it pumps blood throughout the body
HINT
(a) Determine the number of Calories required to power the heart for one day, given that 1 Calorie equals 4186 J.
Cal
(b) Metabolizing 1 kg of fat can release about 9000 Calories of energy. What mass of metabolized fat (in kg) would power the heart for one day?
kg
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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?
Chapter 3 Solutions
Connect with LearnSmart for Krauskopf: The Physical Universe, 16e
Ch. 3 - Which of the following is not a unit of work? a....Ch. 3 - An object at rest may have a. velocity b. momentum...Ch. 3 - A moving object must have which one or more of the...Ch. 3 - When the momentum of a moving object is increased,...Ch. 3 - The total amount of energy (including the rest...Ch. 3 - When the speed of a moving object is halved, a....Ch. 3 - Two balls, one of mass 5 kg and the other of mass...Ch. 3 - A bomb dropped from an airplane explodes in...Ch. 3 - The operation of a rocket is based upon a. pushing...Ch. 3 - A spinning skater whose arms are at her sides then...
Ch. 3 - Prob. 11MCCh. 3 - The formula 12 mv2 for kinetic energy a. is the...Ch. 3 - A spacecraft has left the earth and is moving...Ch. 3 - The upper limit to the speed of an object with...Ch. 3 - It is not true that a. light is affected by...Ch. 3 - Albert Einstein did not discover that a. the...Ch. 3 - The work done in holding a 50-kg object at a...Ch. 3 - The work done in lifting 30 kg of bricks to a...Ch. 3 - A total of 4900 J is used to lift a 50-kg mass....Ch. 3 - The work a 300-W electric grinder can do in 5.0...Ch. 3 - A 150-kg yak has an average power output of 120 W....Ch. 3 - A 40-kg boy runs up a flight of stairs 4 m high in...Ch. 3 - Car A has a mass of 1000 kg and is moving at 60...Ch. 3 - A 1-kg object has a potential energy of 1 J...Ch. 3 - A 1-kg object has kinetic energy of 1 J when its...Ch. 3 - The 2-kg blade of an ax is moving at 60 m/s when...Ch. 3 - The highest MA that can be obtained by a system of...Ch. 3 - A machine has a MA of 6.0. The work input needed...Ch. 3 - A person uses a force of 300 N to pry up one end...Ch. 3 - A 1-kg ball is thrown in the air. When it is 10 m...Ch. 3 - A 10,000-kg freight car moving at 2 m/s collides...Ch. 3 - A 30-kg girl and a 25-kg boy are standing on...Ch. 3 - An object has a rest energy of 1 J when its mass...Ch. 3 - The smallest part of the total energy of the ball...Ch. 3 - The lightest particle in an atom is an electron,...Ch. 3 - A person holds a 10-kg package 1.2 m above the...Ch. 3 - Under what circumstances (if any) is no work done...Ch. 3 - The sun exerts a gravitational force of 4.0 1028...Ch. 3 - A crate is pushed across a horizontal floor at...Ch. 3 - A total of 490 J of work is needed to lift a body...Ch. 3 - A woman eats a cupcake and proposes to work off...Ch. 3 - The acceleration of gravity on the surface of Mars...Ch. 3 - The kilowatt-hour is a unit of what physical...Ch. 3 - The motor of a boat develops 60 kW when the boats...Ch. 3 - How much power must the legs of a 70-kg man...Ch. 3 - A weightlifter raises a 70-kg barbell from the...Ch. 3 - An escalator 14 m long is carrying a 70-kg person...Ch. 3 - A 700-kg horse whose power output is 1.0 hp is...Ch. 3 - A persons metabolic processes can usually operate...Ch. 3 - A crane whose motor has a power input of 5.0 kW...Ch. 3 - A total of 104 kg of water per second flows over a...Ch. 3 - Which of these energies might correspond to the KE...Ch. 3 - What is the speed of an 800-kg car whose KE is 250...Ch. 3 - A moving object whose initial KE is 10 J is...Ch. 3 - Is the work needed to bring a cars speed from 0 to...Ch. 3 - A 1-kg salmon is hooked by a fisherman and it...Ch. 3 - Prob. 22ECh. 3 - How long will it take a 1000-kg car with a power...Ch. 3 - Does every moving body possess kinetic energy?...Ch. 3 - As we will learn in Chap. 6, electric charges of...Ch. 3 - A 60-kg woman jumps off a wall 80 cm high and...Ch. 3 - Why does a nail become hot when it is hammered...Ch. 3 - A 3-kg stone is dropped from a height of 100 m....Ch. 3 - Prob. 29ECh. 3 - Prob. 30ECh. 3 - A ball is dropped from a height of 1 m and loses...Ch. 3 - A person sitting under a coconut palm is struck by...Ch. 3 - A skier is sliding downhill at 8 m/s when she...Ch. 3 - A force of 10 N is used to lift a 600-g ball from...Ch. 3 - A person uses a force of 49 N to raise a 30-kg...Ch. 3 - Prob. 36ECh. 3 - The human forearm is a class III lever. Find the...Ch. 3 - A ramp 20 m long slopes down 1.2 m to the edge of...Ch. 3 - In an effort to lose weight, a person runs 5 km...Ch. 3 - An 80-kg crate is raised 2 m from the ground by a...Ch. 3 - An 800-kg car coasts down a hill 40 m high with...Ch. 3 - (a) When an object at rest explodes into two parts...Ch. 3 - A golf ball and a Ping-Pong ball are dropped in a...Ch. 3 - Is it possible for an object to have more kinetic...Ch. 3 - What happens to the momentum of a car when it...Ch. 3 - The speed of an airplane doubles in flight. (a)...Ch. 3 - When the kinetic energy of an object is doubled,...Ch. 3 - What, if anything, happens to the speed of a...Ch. 3 - A ball of mass m rolling on a smooth surface...Ch. 3 - A railway car is at rest on a frictionless track....Ch. 3 - An empty dump truck coasts freely with its engine...Ch. 3 - A boy throws a 4-kg pumpkin at 8 m/s to a 40-kg...Ch. 3 - A 30-kg girl who is running at 3 m/s jumps on a...Ch. 3 - A 70-kg man and a 50-kg woman are in a 60-kg boat...Ch. 3 - The 176-g head of a golf club is moving at 45 m/s...Ch. 3 - A 40-kg skater moving at 4 m/s overtakes a 60-kg...Ch. 3 - The two skaters of Exercise 56 are moving in...Ch. 3 - A 1000-kg car moving east at 80 km/h collides...Ch. 3 - As the polar ice caps melt, the length of the day...Ch. 3 - All helicopters have two rotors. Some have both...Ch. 3 - The earthquake that caused the Indian Ocean...Ch. 3 - What are the two postulates from which Einstein...Ch. 3 - The theory of relativity predicts a variety of...Ch. 3 - What physical quantity will all observers always...Ch. 3 - The length of a rod is measured by several...Ch. 3 - Under what circumstances does it become...Ch. 3 - Why is it impossible for an object to move faster...Ch. 3 - The potential energy of a golf ball in a hole is...Ch. 3 - What is the effect on the law of conservation of...Ch. 3 - A certain walking person uses energy at an average...Ch. 3 - One kilogram of water at 0C contains 335 kJ of...Ch. 3 - When 1 g of gasoline is burned in an engine, about...Ch. 3 - Approximately 5.4 106 J of chemical energy is...Ch. 3 - Approximately 4 109 kg of matter is converted...
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