Applying Newton's Laws to Friction: Solving Homework Problems

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Homework Help Overview

The discussion revolves around applying Newton's laws to a problem involving friction and forces acting on an object. Participants are exploring the relationships between different forces and their components, particularly in a scenario where kinetic friction is involved.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants are attempting to clarify the direction of the force of kinetic friction and its components. There are questions regarding the total force acting on the object when ignoring friction, and discussions about the interpretation of the problem setup from different perspectives.

Discussion Status

Some participants have offered guidance on how to approach the problem by suggesting to consider the combined forces and their directions. There is an ongoing exploration of different interpretations of the problem setup, with some participants noting that certain interpretations yield answers that match provided choices.

Contextual Notes

There appears to be confusion regarding the interpretation of the forces involved, particularly in terms of their directions and components. The original poster's answer does not align with the available choices, prompting further inquiry into the problem setup.

Fatima Hasan
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Homework Statement


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Homework Equations


F = ma
Fr = uK * N

The Attempt at a Solution


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My answer is 7 but it is not one of the choices

Thanks in advance[/B]
 

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In what direction will the force of kinetic friction act? Don't you have to figure that out before you can determine its components?

Edit: Note that you may be better off starting differently. What is the magnitude of the force from F1 and F2 combined?
 
Fatima Hasan said:
F1 = 5 N
F2 = 20N
That does not answer the question.

Let me ask it another way: "Ignoring friction, what is the magnitude of the total force acting on the object?"
 
jbriggs444 said:
That does not answer the question.

Let me ask it another way: "Ignoring friction, what is the magnitude of the total force acting on the object?"
to the +ve x-axis
so friction is -ve x-axis
 
Fx = F1cos37+F2cos37=20 N
 
Fatima Hasan said:
Fx = F1cos37+F2cos37=20 N
What is the magnitude of the total of the two forces? Not just the X component.

Oh... As I understand the problem, we are looking down at the surface of a table from above. Your understanding is that we are looking from the side with one force pulling diagonally up and one pulling diagonally down?
 
jbriggs444 said:
What is the magnitude of the total of the two forces? Not just the X component.

Oh... As I understand the problem, we are looking down at the surface of a table from above. Your understanding is that we are looking from the side with one force pulling diagonally up and one pulling diagonally down?
yes

Tried your thought, got wrong answer too
 
Last edited:
The "looking down from above" interpretation yields an answer that matches one of the choices.
 
jbriggs444 said:
The "looking down from above" interpretation yields an answer that matches one of the choices.
Thanks.Got it . It's choice C
 
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