Coefficient of Kinetic Friction for crate

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Homework Help Overview

The problem involves a crate being pushed across a level floor at a constant speed, with a focus on determining the coefficient of kinetic friction. The scenario includes a force applied at an angle below the horizontal, which affects the normal force calculation.

Discussion Character

  • Conceptual clarification, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the components of the applied force and how they relate to the normal force. There are attempts to clarify the equations used for calculating the normal force and frictional force, with some questioning the assumptions made in the original calculations.

Discussion Status

There is an ongoing exploration of the correct components of the forces involved. Some participants have offered clarifications regarding the vertical component of the applied force and its impact on the normal force, indicating a productive dialogue without reaching a consensus.

Contextual Notes

Participants are working within the constraints of the problem statement and are addressing potential misunderstandings about the setup, particularly regarding the direction of the applied force and its effects on the normal force calculation.

Tylersaurus
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Homework Statement



A 1500 N crate is being pushed across a level floor at a constant speed by a force F of 700 N at an angle of 20° below the horizontal.

What is the coefficient of kinetic friction between the crate and the floor?

Homework Equations


f=mu(n)

The Attempt at a Solution



I tried 700cos20/1500 + 1500sin20 using the horizontal component of the applied force divided by the normal force, which was mg plus the vertical component of the applied force, but it didn't work, obviously. Any suggestions?
 
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Your description seems right, but your numbers don't look right. The vertical component of the applied force is 700sin20... not 1500sin20
 
Tylersaurus said:

Homework Statement



A 1500 N crate is being pushed across a level floor at a constant speed by a force F of 700 N at an angle of 20° below the horizontal.

What is the coefficient of kinetic friction between the crate and the floor?

Homework Equations


f=mu(n)


The Attempt at a Solution



I tried 700cos20/1500 + 1500sin20 using the horizontal component of the applied force divided by the normal force, which was mg plus the vertical component of the applied force, but it didn't work, obviously. Any suggestions?
I'm not sure of your equations, but the force is applied below the horizontal; you seem to have assumed when calculating the normal force that the applied force is above the horizontal.
 
PhanthomJay said:
I'm not sure of your equations, but the force is applied below the horizontal; you seem to have assumed when calculating the normal force that the applied force is above the horizontal.

no, he assumed it was below the horizontal. He just used 1500 + 1500sin20 for the normal force, instead of 1500 + 700sin20.
 
Yeah, I got that later. Thanks, though.
 

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