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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Textbook Question
Chapter 3, Problem 22MC
A 40-kg boy runs up a flight of stairs 4 m high in 4 s. His power output is
- a. 160 W
- b. 392 W
- c. 40 W
- d. 1568 W
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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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- (a) How long will it take an 850-kg car with a useful power output of 40.0 hp (1hp=746W) to reach a speed of 15.0 m/s, neglecting friction? (b) How long will this acceleration take if the car also climbs a 3.00-m-high hill in the process?arrow_forwardIntegrated Concepts (a) What force must be supplied by an elevator cable to produce an acceleration of 0.800 m/s2 against a 200-N frictional force, if the mass of the loaded elevator is 1500 kg? (b) How much work is done by the cable in lifting the elevator 20.0 m? (c) What is the final speed of the elevator if it starts from rest? (d) How much work went into thermal energy?arrow_forwardA person in good physical condition can put out 100 W of useful power for several hours at a stretch, perhaps by pedaling a mechanism that drives an electric generator. Neglecting any problems of generator efficiency and practical considerations such as resting time: (a) How many people ‘would it take to nm a 4.O0-kW electric clothes dryer? (b) How many people would it take to replace a large electric power plant that generates 800 MW?arrow_forward
- A man of mass 80 kg runs up a flight of stairs 20 m high in 10 s. (a) how much power is used to lift the man?(b) If the man’s body is 25 efficient, how much power does he expend?arrow_forwardA 500-kg dragster accelerates from rest to a final speed of 110 m/s in 400 m (about a quarter of a mile) and encounters an average frictional force of 1200 N. What is its average power output in watts and horsepower if this takes 7.30 s?arrow_forwardWhat is the cost of operating a 3.00-W electric clock for a year if the cost of electricity is 0.0900 per kWh ?arrow_forward
- (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.arrow_forwardWhat average power is generated by a 70.0-kg moun-tain climber who climbs a summit of height 325 in in 95.0 min? (a) 39.1 W (b) 54.6 W (c) 25.5 W (d) 67.0 W (e) 88.4 Warrow_forwardAn archer pulls her bowstring back 0.400 m by exerting a force that increases uniformly from zero to 230 N. (a) What is the equivalent spring constant of the bow? (b) How much work does the archer do on the string in drawing the bow?arrow_forward
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