Incredibly complicated for basic physics

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Homework Help Overview

The problem involves a book placed on a table, where the user applies a downward force with one hand while pushing the book horizontally with the other hand at constant speed. The coefficients of kinetic friction between the book and the table, as well as between the user's hand and the book, are provided, along with the mass of the book and the downward force applied.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the relationship between the forces acting on the book, particularly focusing on the effects of friction and the condition of constant velocity. There is an emphasis on understanding how to set up the equations of motion correctly.

Discussion Status

The discussion is ongoing, with some participants providing guidance on the importance of recognizing that the acceleration is zero due to constant speed. Others have requested to see the original poster's work to better assist in identifying where they may be stuck.

Contextual Notes

There is a mention of the need to consider the normal force when calculating kinetic friction, indicating that participants are exploring the implications of the problem's constraints and definitions.

JAK3CAL
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Homework Statement




You place a book flat on a table and press down on it with your right hand. The hand-to-book and table-to-book coefficients of kinetic friction are 0.47 and 0.44 respectively. The book's mass is 0.84 kg and your downward push on it is 9.00 N. Now, you use your left hand to push the book along the table at constant speed. Assuming that your right hand is stationary with respect to the table, what is the horizontal force exerted on the book by your left hand?


Homework Equations





The Attempt at a Solution



think its got something to do with the fact that the two friction coefficients are like a sandwich on the book. the x direction equation is the force you push the book with minus the two frictions added together= mass times acceleration but I can't get it to work. HELPPPPPPPPPPPPPPP I've spent an hour on this any push in the right direction is appreciated before I lose my damn mind
 
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JAK3CAL said:
the x direction equation is the force you push the book with minus the two frictions added together= mass times acceleration
Yes, that much is correct. But don't forget the problem statement says, "use your left hand to push the book along the table at constant speed." What is the acceleration of something moving at a constant velocity?

You've mentioned that you've worked on this for an hour. So show us your work! :smile: Maybe we can help you once we see what you've done specifically, and where you are stuck.
 
You must remember that kinetic friction has a dependence of the Normal Force (N). So if you sum the forces in the x direction you get :

Fx = Fh - Fk= ma; (Fh = Force by hand; Fx = force of friction) what is acceleration if it is constant?Kinetic Friction is =\muk*NYou can now plug in your frictional force, and solve for the force due to your hand
 
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