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Physics (5th Edition)
5th Edition
ISBN: 9780321976444
Author: James S. Walker
Publisher: PEARSON
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Textbook Question
Chapter 7, Problem 2PCE
A pendulum bob swings from point II to point III along the circular arc indicated in Figure 7-19. (a) Is the work done on the bob by gravity positive negative, or zero? Explain. (b) Is the work done on the bob by the string positive negative or zero? Explain.
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Chapter 7 Solutions
Physics (5th Edition)
Ch. 7.1 - Enhance Your Understanding (Answers given at the...Ch. 7.2 - Enhance Your Understanding (Answers given at the...Ch. 7.3 - As an object moves along the positive x axis the...Ch. 7.4 - Enhance Your Understanding (Answers given at the...Ch. 7 - Is it possible to do work on an object that...Ch. 7 - A friend makes the statement, Only the total force...Ch. 7 - A friend makes the statement, A force that is...Ch. 7 - The net work done on a certain object is zero What...Ch. 7 - Give an example of a frictional force doing...Ch. 7 - A ski boat moves with constant velocity Is the net...
Ch. 7 - A package rests on the floor of an elevator that...Ch. 7 - An object moves with constant velocity Is it safe...Ch. 7 - Engine 1 does twice the work of engine 2. Is it...Ch. 7 - Engine 1 produces twice the power of engine 2. Is...Ch. 7 - A pendulum bob swings from point I to point II...Ch. 7 - A pendulum bob swings from point II to point III...Ch. 7 - A farmhand pushes a 26-kg bale of hay 3.9 m across...Ch. 7 - Children in a tree house lift a small dog in a...Ch. 7 - Early one October, you go to a pumpkin patch to...Ch. 7 - The coefficient of kinetic friction between a...Ch. 7 - BIO Peristaltic Work The human snail intestine...Ch. 7 - Predict/Calculate A tow rope, parallel to the...Ch. 7 - A child pulls a friend in a little red wagon with...Ch. 7 - A 57-kg packing crate is pulled with constant...Ch. 7 - Predict/Calculate To clean a floor, a janitor...Ch. 7 - A small plane tows a glider at constant speed and...Ch. 7 - As a snowboarder descends a mountain slope,...Ch. 7 - A young woman on a skateboard is pulled by a rope...Ch. 7 - To keep her dog from running away while she talks...Ch. 7 - Water skiers often ride to one side of the center...Ch. 7 - A pitcher throws a ball at 90 mi/h and the catcher...Ch. 7 - How much work is needed for a 73 kg runner to...Ch. 7 - Skylabs Reentry When Skylab reentered the Earths...Ch. 7 - Predict/Calculate A 9.50-g bullet has a speed of...Ch. 7 - The energy required to increase the speed of a...Ch. 7 - Predict/Explain The work W0 accelerates a car...Ch. 7 - Car A has a mass m and a speed u, car B has a mass...Ch. 7 - Predict/Calculate A 0.14-kg pinecone falls 16 m to...Ch. 7 - In the previous problem (a) how much work was done...Ch. 7 - At t = 1.0s, a 0.55-kg object is tailing with a...Ch. 7 - After hitting a long fly ball that goes over the...Ch. 7 - Predict/Calculate A 1100-kg car coasts on a...Ch. 7 - A 65-kg bicyclist rides his 8 8-kg bicycle with a...Ch. 7 - A block of mass m and speed U collides with a...Ch. 7 - A spring with a force constant of 3.5 104 N/m is...Ch. 7 - Initially sliding with a speed of 4.1 m/s, a...Ch. 7 - The force shown in Figure 7-21 moves an object...Ch. 7 - An object is acted on by the force shown in Figure...Ch. 7 - To compress spring 1 by 0 20 m takes 150 J of...Ch. 7 - Predict/Calculate It takes 180 J of work to...Ch. 7 - The force shown in Figure 7-22 acts on a 1.3-kg...Ch. 7 - A block is acted on by a force that varies as (2.0...Ch. 7 - Section 7-4 Power 42 CE Fore F1 does 5 J of work...Ch. 7 - BIO Climbing the Empire State Building A new...Ch. 7 - Calculate the power output of a 14-mg fly as it...Ch. 7 - An ice cube is placed in a microwave oven. Suppose...Ch. 7 - Your car produces about 34 kw of power to maintain...Ch. 7 - You raise a bucket of water from the bottom of a...Ch. 7 - BIO Salmon Migration As Chinook salmon swim...Ch. 7 - In order to keep a leaking ship from sinking, it...Ch. 7 - Predict/Calculate A kayaker paddles with a power...Ch. 7 - BIO Human-Powered Flight Human-powered aircraft...Ch. 7 - Predict/Calculate Beating to Windward A sailboat...Ch. 7 - Predict/Calculate A grandfather clock is powered...Ch. 7 - Prob. 54PCECh. 7 - CE As the three small sailboats shown in Figure...Ch. 7 - CE Predict/Explain A car is accelerated by a...Ch. 7 - CE Car 1 has four limes the mass of car 2, but...Ch. 7 - BIO Muscle Cells Biological muscle cells can be...Ch. 7 - A small motor runs a lift that raises a load of...Ch. 7 - You push a 67-kg box across a door where the...Ch. 7 - A 1300-kg elevator is lifted at a constant speed...Ch. 7 - CE The work W0 is required to accelerate a car...Ch. 7 - After a tornado a 0.55-g straw was found embedded...Ch. 7 - You throw a glove straight upward to celebrate a...Ch. 7 - The water skier in Figure 7-20 is at an angle of...Ch. 7 - Predict/Calculate A sled with a mass of 5.80 kg is...Ch. 7 - Predict/Calculate A 0.19-kg apple falls from a...Ch. 7 - A boy pulls a bag of baseball bats across a ball...Ch. 7 - At the instant it leaves the players hand after a...Ch. 7 - The force shown in Figure 7-25 acts on an object...Ch. 7 - A Compound Bow A compound bow in archery allows...Ch. 7 - A Compound Versus a Simple Bow The compound bow in...Ch. 7 - Calculate the power output of a 0.42-g spider as...Ch. 7 - Cookie Power To make a batch of cookies, you mix...Ch. 7 - Predict/Calculate A pitcher accelerates a 0.14-kg...Ch. 7 - BIO Brain Power The human brain consumes about 22...Ch. 7 - Meteorite On October 9, 1992, a 27-pound meteorite...Ch. 7 - BIO Powering a Pigeon A pigeon in flight...Ch. 7 - Springs in Series Two springs, with force...Ch. 7 - Springs in Parallel Two springs, with force...Ch. 7 - A block rests on a horizontal frictionless...Ch. 7 - BIO Microraptor gui: The Biplane Dinosaur The...Ch. 7 - BIO Microraptor gui: The Biplane Dinosaur The...Ch. 7 - BIO Microraptor gui: The Biplane Dinosaur The...Ch. 7 - BIO Microraptor gui: The Biplane Dinosaur The...Ch. 7 - Referring to Figure 7-15 Suppose the block has a...Ch. 7 - Predict/Calculate Referring to Figure 7-15 In the...Ch. 7 - Predict/Calculate Referring 10 Example 7-15...
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- (a) A force F=(4xi+3yj), where F is in newtons and x and y are in meters, acts on an object as the object moves in the x direction from the origin to x = 5.00 m. Find the work W=Fdr done by the force on the object. (b) What If? Find the work W=Fdr done by the force on the object if it moves from the origin to (5.00 m, 5.00 m) along a straightline path making an angle of 45.0 with the positive x axis. Is the work done by this force dependent on the path taken between the initial and final points?arrow_forward(a) Can the kinetic energy of a system be negative? (b) Can the gravitational potential energy of a system be negative? Explain.arrow_forwardA shopper pushes a grocery cart 20.0 m at constant speed on level ground, against a 35.0 N frictional force. He pushes in a direction 25.0° below the horizontal. (a) What is the work done on the cart by friction? (b) What is the work done on the cart by the gravitational force? (c) What is the work done on the cart by the shopper? (d) Find the force the shopper exerts, using energy considerations. (e) What is the total work done on the cart?arrow_forward
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