College Physics 1st Edition
ISBN: 9781938168000
Author: Paul Peter Urone, Roger Hinrichs
Publisher: Paul Peter Urone, Roger Hinrichs
1 Introduction: The Nature Of Science And Physics 2 Kinematics 3 Two-dimensional Kinematics 4 Dynamics: Force And Newton's Laws Of Motion 5 Further Applications Of Newton's Laws: Friction, Drag, And Elasticity 6 Uniform Circular Motion And Gravitation 7 Work, Energy, And Energy Resources 8 Linear Momentum And Collisions 9 Statics And Torque 10 Rotational Motion And Angular Momentum 11 Fluid Statics 12 Fluid Dynamics And Its Biological And Medical Applications 13 Temperature, Kinetic Theory, And The Gas Laws 14 Heat And Heat Transfer Methods 15 Thermodynamics 16 Oscillatory Motion And Waves 17 Physics Of Hearing 18 Electric Charge And Electric Field 19 Electric Potential And Electric Field 20 Electric Current, Resistance, And Ohm's Law 21 Circuits And Dc Instruments 22 Magnetism 23 Electromagnetic Induction, Ac Circuits, And Electrical Technologies 24 Electromagnetic Waves 25 Geometric Optics 26 Vision And Optical Instruments 27 Wave Optics 28 Special Relativity 29 Introduction To Quantum Physics 30 Atomic Physics 31 Radioactivity And Nuclear Physics 32 Medical Applications Of Nuclear Physics 33 Particle Physics 34 Frontiers Of Physics Chapter7: Work, Energy, And Energy Resources
Chapter Questions Section: Chapter Questions
Problem 1CQ: Give an example of something think of as work in everyday circumstances that is not work in the... Problem 2CQ: Give an example of a situation in which there is a force and a displacement, but the force does no... Problem 3CQ: Describe a situation in which a force is exerted for a long time but does no work. Explain. Problem 4CQ: The person in Figure 7.33 does work on the lawn mower. Under what conditions would the mower gain... Problem 5CQ: Work done on a system puts energy into it Work done by a system removes energy from it Give an... Problem 6CQ: When solving for speed in Example 7.4, we kept only the positive root. Why? Problem 7CQ: In Example 7.7, we calculated the final speed of a roller coaster that descended 20m in height and... Problem 8CQ: Does the work you do on a book when you lift it onto a shelf depend on the path taken? On the time... Problem 9CQ: What is a conservative force? Problem 10CQ: The force exerted by a diving board is conservative, provided the internal friction is negligible.... Problem 11CQ: Define mechanical energy. What is the relationship of mechanical energy to non-conservative forces?... Problem 12CQ: What is the relationship of potential energy to conservative force? Problem 13CQ: Consider the following scenario. A car for which friction is not negligible accelerates from rest... Problem 14CQ: Describe the energy transfers and transformations for a javelin, stating from the point at which an... Problem 15CQ: Do devices with efficiencies of less than one violate the law of conservation of energy? Explain. Problem 16CQ: List four different forms or types of energy. Give one example of a conversion from each of these... Problem 17CQ: List the energy conversions that occur when riding a bicycle. Problem 18CQ: Most electrical appliances are rated in watts. Does this rating depend on how long the appliance is... Problem 19CQ: Explain, in terms of the definition of power, why energy consumption is sometimes listed in... Problem 20CQ: A spark of static electricity, such as that you might receive from a doorknob on a cold dry day, may... Problem 21CQ: Explain why it is easier to climb a mountain on a zigzag path rather than one straight up the side.... Problem 22CQ: Do you do work on the outside world when you rub your hands together to warn) then)? What is the... Problem 23CQ: Shivering is an involuntary response to lowered body temperature. What is the efficiency of the body... Problem 24CQ: Discuss the relative effectiveness of dieting and exercise in losing weight, noting that most... Problem 25CQ: What is the difference between energy conservation and the law of conservation of energy? Give some... Problem 26CQ: If the efficiency of a coal-fired electrical generating plant is 35%, then what do we mean when we... Problem 1PE: How much work does a supermarket checkout attendant do on a can of soup he pushes 0.600 m... Problem 2PE: A 75.0-kg person climbs stairs, gaining 2.50 meters in height. Find the work done to accomplish this... Problem 3PE: (a) Calculate the work done on a 1500-kg elevator car by its cable to lift it 40.0 m at constant... Problem 4PE: Suppose a car travels 108 km at a speed of 30.0 m/s, and uses 2.0 gal of gasoline. Only 30% of the... Problem 5PE: Calculate the work done by an 85.0-kg man who pushes a crate 4.00 m up along a ramp that makes an... Problem 6PE: How much work is done by the boy pulling his sister 30.0 m in a wagon as shown in Figure 7.36?... Problem 7PE: A shopper pushes a grocery cart 20.0 m at constant speed on level ground, against a 35.0 N... Problem 8PE: Suppose the ski patrol lowers a rescue sled and victim, having a total mass of 90.0 kg, down a 60.0°... Problem 9PE: Compare the kinetic energy of a 20,000-kg truck moving at 110 km/h with that of an 80.0-kg astronaut... Problem 10PE: (a) How fast must a 3000-kg elephant move to have the same kinetic energy as a 65.0-kg sprinter... Problem 11PE: Confirm the value given for the kinetic energy of an aircraft carrier in Table 7.1. You will need to... Problem 12PE: (a) Calculate the force needed to bring a 950-kg car to rest from a speed of 90.0 km/h in a distance... Problem 13PE: A car's bumper is designed to withstand a 4.0-km/h (1.1-m/s) collision with an immovable object... Problem 14PE: Boxing gloves are padded to lessen the force of a blow. (a) Calculate the force exerted by a boxing... Problem 15PE: Using energy considerations, calculate the average force a 60.0-kg sprinter exerts backward on the... Problem 16PE: A hydroelectric power facility (see Figure 7.38) converts the gravitational potential energy of... Problem 17PE: (a) How much gravitational potential energy (relative to the ground on which it is built) is stored... Problem 18PE: Suppose a 350-g kookaburra (a large kingfisher bird) picks up a 75-g snake and raises it 2.5 m from... Problem 19PE: In Example 7.7, we found that the speed of a roller coaster that had descended 20.0 m was only... Problem 20PE: A 100-g toy car is propelled by a compressed spring that starts it moving. The car follows the... Problem 21PE: In a downhill ski race, surprisingly, little advantage is gained by getting a running start. (This... Problem 22PE: A 5.00105 -kg subway train is brought to a stop from a speed of 0.500 m/s in 0.400 m by a large... Problem 23PE: A pogo stick has a spring with a force constant of 2.50104 N/m, which can be compressed 12.0 cm. To... Problem 24PE: A 60.0-kg skier with an initial speed of 12.0 m/s coasts up a 2.50-m-high rise as shown in Figure... Problem 25PE: (a) How high a hill can a car coast up (engine disengaged) if work done by friction is negligible... Problem 26PE: Using values from Table 7.1, how many DNA molecules could be broken by the energy carried by a... Problem 27PE: Using energy considerations and assuming negligible air resistance, show that a rock thrown from a... Problem 28PE: If the energy in fusion bombs were used to supply the energy needs of the world, how many of the... Problem 29PE: (a) Use of hydrogen fusion to supply energy is a dream that may be realized in the next century.... Problem 30PE: The Crab Nebula (see Figure 7.41) pulsar is the remnant of a supernova that occurred in A.D. 1054.... Problem 31PE: Suppose a star 1000 times brighter than our Sun (that is, emitting 1000 times the power) suddenly... Problem 32PE: A person in good physical condition can put out 100 W of useful power for several hours at a... Problem 33PE: What is the cost of operating a 3.00-W electric clock for a year if the cost of electricity is... Problem 34PE: A large household air conditioner may consume 15.0 kW of power. What is the cost of operating this... Problem 35PE: (a) What is the average power consumption in watts of an appliance that uses 5.00 kW h of energy... Problem 36PE: (a) What is the average useful power output of a person who does 6.00106 J of useful work in 8.00 h?... Problem 37PE: A 500-kg dragster accelerates from rest to a final speed of 110 m/s in 400 m (about a quarter of a... Problem 38PE: (a) How long will it take an 850-kg car with a useful power output of 40.0 hp (1hp=746W) to reach a... Problem 39PE: (a) Find the useful power output of an elevator motor that lifts a 2500-kg load a height of 35.0 m... Problem 40PE: (a) What is the available energy content, in joules, of a battery that operates a 2.00-W electric... Problem 41PE: (a) How long would it takea 1.50105 -kg airplane with engines that produce 100 MW of power to reach... Problem 42PE: Calculate the power output needed for a 950-kg car to climb a 2.00° slope at a constant 30.0 m/s... Problem 43PE: (a) Calculate the power per square meter reaching Earth's upper atmosphere from the Sun. (Take the... Problem 44PE: (a) How long can you rapidly climb stairs (116/min) on the 93.0 kcal of energy in a 10.0-g pat of... Problem 45PE: (a) What is the power output in watts and horsepower of a 70.0-kg sprinter who accelerates from rest... Problem 46PE: Calculate the power output in watts and horsepower of a shot-putter who takes 1.20 s to accelerate... Problem 47PE: (a) What is the efficiency of an out-of-condition professor who does 2.10105J of useful work while... Problem 48PE: Energy that is not utilized for work or heat transfer is converted to the chemical energy of body... Problem 49PE: Using data from Table 7.5, calculate the daily energy needs of a person who sleeps for 7.00 h, walks... Problem 50PE: What is the efficiency of a subject on a treadmill who puts out work at the rate of 100 W while... Problem 51PE: Shoveling snow can be extremely taxing because the arms have such a low efficiency in this activity.... Problem 52PE: Very large forces are produced in joints when a person jumps from some height to the ground. (a)... Problem 53PE: Jogging on hard surfaces with insufficiently padded shoes produces large forces in the feet and... Problem 54PE: (a) Calculate the energy in kJ used by a 55.0-kg woman who does 50 deep knee bends in which her... Problem 55PE: Kanellos Kanellopoulos flew 119 km from Crete to Santorini, Greece, on April 23, 1988, in the... Problem 56PE: The swimmer shown in Figure 7.44 exerts an average horizontal backward force of 80.0 N with his arm... Problem 57PE: Mountain climbers carry bottled oxygen when at very high altitudes. (a) Assuming that a mountain... Problem 58PE: The awe-inspiring Great Pyramid of Cheops was built more than 4500 years ago. Its square base,... Problem 59PE: (a) How long can you play tennis on the 800 kJ (about 200 kcal) of energy in a candy bar? (b) Does... Problem 60PE: Integrated Concepts (a) Calculate the force the woman in Figure 7.46 exerts to do a push-up at... Problem 61PE: Integrated Concepts A 75.0-kg cross-country skier is climbing a 3.0° slope at a constant speed of... Problem 62PE: Integrated Concepts The 70.0-kg swimmer in Figure 7.44 starts a race with an initial velocity of... Problem 63PE: Integrated Concepts A toy gun uses a spring with a force constant of 300 N/m to propel a 10.0-g... Problem 64PE: Integrated Concepts (a) What force must be supplied by an elevator cable to produce an acceleration... Problem 65PE: Unreasonable Results A car advertisement claims that its 900-kg car accelerated from rest to 30.0... Problem 66PE: Unreasonable Results Body fat is metabolized, supplying 9.30 kcal/g, when dietary intake is less... Problem 67PE: Construct Your Own Problem Consider a person climbing and descending stairs. Construct a problem in... Problem 68PE: Construct Your Own Problem Consider humans generating electricity by pedaling a device similar to a... Problem 69PE: Integrated Concepts A 105-kg basketball player crouches down 0.400 m while waiting to jump. After... Problem 61PE: Integrated Concepts A 75.0-kg cross-country skier is climbing a 3.0° slope at a constant speed of...
Related questions
A hummingbird hovers by exerting a downward force on the air equal, on average, to its weight. By Newton's third law , the air exerts an upward force of the same magnitude on the bird's wings. Find the average mechanical power (in W) delivered by a 2.80 g hummingbird while hovering if its wings beat 75.0 times per second through a stroke 3.02 cm long.
HINT
W
Definition Definition Fundamental law of forces which states: “For every action, there is an equal and opposite reaction." In other words, whenever one body exerts a force on a second body, the second body exerts an oppositely directed force of equal magnitude on the first body. It is also called the “action-reaction law” and was defined by Sir Isaac Newton.
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