18th Edition

ISBN: 9781938168277

Author: William Moebs, Samuel J. Ling, Jeff Sanny

Publisher: OpenStax - Rice University

Concept explainers

A machine is a device that accepts energy in some available form and utilizes it to do a type of work. Energy, work, or power has to be transferred from one mechanical part to another to run a machine. While the transfer of energy between two machine par…

Kinetic Energy and Work-Energy Theorem

In physics, work is the product of the net force in direction of the displacement and the magnitude of this displacement or it can also be defined as the energy transfer of an object when it is moved for a distance due to the forces acting on it in the d…

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Textbook Question

Chapter 7, Problem 45P

(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.

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Chapter 7, Problem 44P

Chapter 7, Problem 46P

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Chapter 7 Solutions

University Physics Volume 1

Ch. 7 - Describe a situation in 4iich a force is exerted...Ch. 7 - A body moves in a circle at constant speed. Does...Ch. 7 - Suppose you throw a ball upward and catch it when...Ch. 7 - Why is it more difficult to do sit-ups while on a...Ch. 7 - As a young man, Tarzan climbed up a vine to reach...Ch. 7 - A particle of m has a velocity of . Is its kinetic...Ch. 7 - One particle has mass mand a second particle has...Ch. 7 - A person drops a pebble of mass m1from a height h,...Ch. 7 - The person shown below does work on the lawn...Ch. 7 - Work done on a system puts energy into it. Work...Ch. 7 - Two marbles of masses mand 2mare dropped from a...Ch. 7 - Compare the work required to accelerate a car of...Ch. 7 - Suppose you are jogging at constant velocity. Are...Ch. 7 - Two forces act to double the speed of a particle,...Ch. 7 - Most electrical appliances are rated in watts....Ch. 7 - Explain, in terms of the definition of power, why...Ch. 7 - A spark of static electricity, such as that you...Ch. 7 - Does the work done in lifting an object depend on...Ch. 7 - Can the power expended by a force be negative?Ch. 7 - How can a 50-W light bulb use more energy than a...Ch. 7 - Work How much work does a supermarket checkout...Ch. 7 - A 75.0-kg person climbs stairs, gaining 2.50 m in...Ch. 7 - (a) Calculate the work done on a 1500-kg elevator...Ch. 7 - Suppose a car travels 108 km at a speed of 30.0...Ch. 7 - Calculate the work done by an 85.0-kg man who...Ch. 7 - How much work is done by the boy pulling his...Ch. 7 - A shopper pushes a grocery cart 20.0 m at constant...Ch. 7 - Suppose the ski patrol lowers a rescue sled and...Ch. 7 - A constant 20-N force pushes a small ball in the...Ch. 7 - A toy cart is pulled a distance of 6.0 m in a...Ch. 7 - A 5.0-kg box rests on a horizontal surface. The...Ch. 7 - A sled plus passenger with total mass 50 kg is...Ch. 7 - Suppose that the sled plus passenger of the...Ch. 7 - How much work does the force do on a particle as...Ch. 7 - How much work is done against the gravitationaI...Ch. 7 - It takes 500 J of work to compress a spring 10 cm....Ch. 7 - A bungee cord is essentially a very long rubber...Ch. 7 - A bungee cord exerts a nonlinear elastic force of...Ch. 7 - Engineers desire to model the magnitude of the...Ch. 7 - A particle moving in the xy -plane is subject to a...Ch. 7 - A particle moves along a curved path...Ch. 7 - Kinetic Energy Compare the kinetic energy of a...Ch. 7 - (a) How fast must a 3000-kg elephant move to have...Ch. 7 - Estimate the kinetic energy of a 90,000-ton...Ch. 7 - Calculate the kinetic energies of (a) a 2000.0-kg...Ch. 7 - A 5.0-kg body has three times the kinetic energy...Ch. 7 - An 8.0-g bullet has a speed of 800 m/s. (a) What...Ch. 7 - (a) Calculate the force needed to bring a 950-kg...Ch. 7 - A car’s bumper is designed to withstand a 4.0-km/...Ch. 7 - Boxing gloves are padded to lessen the force of a...Ch. 7 - Using energy considerations, calculate the average...Ch. 7 - A 5.0-kg box has an acceleration of 2.0m/s2 when...Ch. 7 - A constant 10-N horizontal force is applied to a...Ch. 7 - In the preceding problem, the 10-N force is...Ch. 7 - Compare the work required to stop a 100-kg crate...Ch. 7 - A wagon with its passenger sits at the top of a...Ch. 7 - An 8.0-g bullet with a speed of 800 m/s is shot in...Ch. 7 - A 2.0-kg block starts with a speed of 10 m/s at...Ch. 7 - When a 3.0-kg block is pushed against a massless...Ch. 7 - A small block of mass 200 g starts at rest at A,...Ch. 7 - A small object is placed at the top of an incline...Ch. 7 - When released, a 100-g block slides down the path...Ch. 7 - A 0.22LR-caliber bullet like that mentioned in...Ch. 7 - A sled stalls from rest at the top of a...Ch. 7 - A person in good physical condition can put out...Ch. 7 - What is the cost of operating a 3.00-W electric...Ch. 7 - A large household air conditioner may consume 15.0...Ch. 7 - (a) What is the average power consumption in watts...Ch. 7 - (a) What is the average useful power output of a...Ch. 7 - A 500-kg dragster accelerates from rest to a final...Ch. 7 - (a) How long will it take an 850-kg car with a...Ch. 7 - (a) Fir the useful power output of an elevator...Ch. 7 - (a) How long would it take a 1.50105kg airplane...Ch. 7 - Calculate the power output needed for a 950-kg car...Ch. 7 - A man of mass 80 kg runs up a flight of stairs 20...Ch. 7 - The man of the preceding problem consumes...Ch. 7 - An electron in a television tube is accelerated...Ch. 7 - Coal is lifted out of a mine a vertical distance...Ch. 7 - A girl pulls her 15-kg wagon along a flat sidewalk...Ch. 7 - A typical automobile engine has an efficiency of...Ch. 7 - When jogging at 13 km/h on a level surface, a...Ch. 7 - A cart is pulled a distance D on a flat,...Ch. 7 - Consider a particle on which several forces act,...Ch. 7 - Consider a particle on which several forces act,...Ch. 7 - Consider a particle on which several forces act,...Ch. 7 - Consider a particle on which a force acts that...Ch. 7 - A boy pulls a 5-kg cart with a 20-N force at an...Ch. 7 - A crate of mass 200 kg is to be bright from a site...Ch. 7 - At hokey puck of mass 0.17 kg is shot across a...Ch. 7 - A horizontal force of 20 N is required to keep a...Ch. 7 - A 7.0-kg box slides along a horizontal...Ch. 7 - You are driving your car on a straight road with a...Ch. 7 - A crate is being pushed across a rough floor...Ch. 7 - Suppose a horizontal force of 20 N is required to...Ch. 7 - Grains from a hopper falls at a rate of 10 kg/s...Ch. 7 - A cyclist in a race must climb a 5 hill at a speed...Ch. 7 - Shown below is a 40-kg crate that is pushed at...Ch. 7 - The surface of the preceding problem is modified...Ch. 7 - The force F(x) varies with position, as shown...Ch. 7 - Find the work done by the same force in Example...Ch. 7 - Answer the preceding problem using polar...Ch. 7 - Find the work done by the same force in Example...Ch. 7 - Answer the preceding problem using polar...Ch. 7 - Constant power P is delivered to a car of mass m...Ch. 7 - Suppose that the air resistance a car encounters...Ch. 7 - Consider a linear spring, as in Figure 7.7(a),...

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