What Is the Correct Coefficient of Friction Calculation?

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Homework Help Overview

The discussion revolves around calculating the coefficient of friction for a block being pushed along a surface and determining the weight of an additional block placed on top. The subject area includes concepts of friction and forces in physics.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the correct force values to use in the friction equation and question the initial calculations. There is a focus on verifying the coefficient of friction and its application in subsequent calculations for the weight of an additional block.

Discussion Status

Participants are actively engaging in verifying calculations and discussing the implications of their results. Some guidance has been offered regarding rounding answers for significant figures, indicating a productive direction in the discussion.

Contextual Notes

There is a mention of assumptions regarding the direction of the applied force and the need for clarity on the correct force values used in calculations. The context suggests that participants are working within a homework framework that may impose specific requirements on their answers.

anglum
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A block weighing 8.1 N requires a force of
2.8 N to push it along at constant velocity.
What is the coeficient of friction for the
surface?

002 (part 2 of 2) 10 points
A weight W is now placed on the block and
4.8 N is needed to push them both at constant
velocity.
What is the weight W of the block? Answer
in units of N.



For part 1 i used the equation 2.1N = Cf * 8.1N
and solved for Cf or coefficient of friction

that was incorrect tho
 
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anglum said:
For part 1 i used the equation 2.1N = Cf * 8.1N
and solved for Cf or coefficient of friction
Shouldn't that be 2.8 N? (Assuming the force is applied horizontally.)
 
yeah i mistyped that it should be

2.8N = Friction * 8.1N

Friction = .34567 ?

is that correct? if i have that then i can solve the 2nd one

by taking
4.8= .345679 *(8.1N+W) and solve for W?
 
and in solving for W there i get 5.7857 N
 
Looks good to me. (You may want to round off your answer to a reasonable number of significant figures--especially if you're using an online system.)
 

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