Cutnell and Johnson - Physics 8/e (Homework)

Chris Read

Wiley, section 1, Fall 2010

Instructor: Mr. Wiley

Current Score: 5/10

Due: Saturday, September 4, 2010 08:00 PM EDT

About this Assignment

Question
Points
1 2 3 4 5
1 0/1 4 0/1 0/3
Total
5/10

Description

Physics 8/e by Cutnell and Johnson published by John Wiley & Sons, Inc. is now a WebAssign Plus selection. WebAssignPLUS includes a complete on-line version of the text, the Student Study Guide, the Student Solutions Manual, and a variety of interactive study aids. All of these rich resources are linked together in a dynamic and interactive environment for students. Additional links to the eBook within each problem are structured to support the way students work and provide them with superior just-in-time learning resources. Also the eBook availability provides students with a significantly less expensive option than the printed version.

The first question is a Focus on Concept multiple choice question. These questions offer conceptual feedback on every incorrect and correct choice. A selection of these are available exclusively online.

Questions 2 and 4 are standard end of chapter questions.

Question 3 is a end of chapter problem that is enhanced with an optional Guided Online (GO) tutorial. Each GO tutorial steps a student through a similar question with feedback enhanced multiple choice questions similar to the Focus on Concept questions. Other questions within the tutorial help students solve the problem symbolically to aid in mastering the underlying concepts involved in the problem

Question 5 is a simulation problem with a link to a simulation that will help the student visualize the concept.

To see a demo of chapter 4 of the online book, click Home and select the Wiley Online Books class from the pulldown menu. If you adopt Cutnell and Johnson, your students will see an option to purchase the online book on their WebAssign Homepage.

Click here for a list of all of the questions coded in WebAssign.


Instructions

This demo assignment allows many submissions and allows you to try another version of the same question for practice.



1. 1/1 points All Submissions Notes Question: CJ8 4.FC.014.
Question part
Points
Submissions
1
1
2/50
Total
1/1
 
The drawings show identical blocks at rest on three different inclines, each block held in place by static friction. Rank the forces of static friction in the three cases in ascending order (smallest first).
    

Your answer is correct.


Correct. The static frictional force is balancing the component of the block's weight that points down the slope of the incline. This component is smallest in B and greatest in A.

2. 0/1 points All Submissions Notes Question: CJ8 4.P.039.
Question part
Points
Submissions
1
0/1
3/50
Total
0/1
 
A student presses a book between his hands, as the drawing indicates. The forces that he exerts on the front and back covers of the book are perpendicular to the book and are horizontal. The book weighs 29 N. The coefficient of static friction between his hands and the book is 0.36. To keep the book from falling, what is the magnitude of the minimum pressing force that each hand must exert?
Enter a number.
Your answer is incorrect. N


3. 4/4 points All Submissions Notes Question: CJ8 4.P.044.GO.
Question part
Points
Submissions
1 2 3 4 5 6 7 8 9 10 11 12
1 1 1 1 0 0 0 0 0 0 0 0
4/50 1/50 2/50 1/50 0/50 0/50 0/50 0/50 0/50 0/50 0/50 0/50
Total
4/4
 
A person pushes on a 62-kg refrigerator with a horizontal force of -266 N; the minus sign indicates that the force points in the -x direction. The coefficient of static friction is 0.61.
(a) If the refrigerator does not move, what are the magnitude and direction of the static frictional force that the floor exerts on the refrigerator?
Static frictional force =
Enter a number.
Your answer is correct. 		Your answer is correct.

(b) What is the magnitude of the largest pushing force that can be applied to the refrigerator before it just begins to move? Assume g = 9.81 m/s2.
Magnitude of largest force =
Enter a number.
Your answer is correct. 		Your answer is correct.
GO Tutorial

4. –/1 points Notes Question: CJ8 4.P.064.
Question part
Points
Submissions
1
0/1
0/50
Total
0/1
 
The person in the drawing is standing on crutches. Assume that the force exerted on each crutch by the ground is directed along the crutch, as the force vectors in the drawing indicate. If the coefficient of static friction between a crutch and the ground is 0.70, determine the largest angle θMAX that the crutch can have just before it begins to slip on the floor.
Enter a number.
°


5. –/3 points Notes Question: CJ8 4.SIM.05.
Question part
Points
Submissions
1 2 3
0/1 0/1 0/1
0/50 0/50 0/50
Total
0/3
 
Note: Use principles of physics to solve the problem and then verify your answer using the simulation.
You are traveling along a road at 90 km/hr, maintaining a constant distance d between you and the car in front of you, measured from your front bumper to the other car's rear bumper.
(a) If the driver of the car in front of you applies the brakes to come to a complete stop, what is the minimum value of d required if you are not to hit the other car? Assume your reaction time (the time it takes you to see the brake lights in front and apply your own brakes) is 0.30 s and that the appropriate coefficient of friction between the road and your car tires is 0.89. Assume the acceleration due to gravity has a magnitude of 9.8 m/s2.
Enter a number.
 m

(b) Assuming the length of a typical car is 3.00 m, express the minimum value of d in car lengths.
Enter a number.
 car lengths.

(c) What is the distance between the two cars at the instant you apply the brakes?
Enter a number.
 m

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