How much work done by friction when a box w/apparent mass...?

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Homework Help Overview

The problem involves calculating the work done by friction on a box with an apparent mass of 325 kg moving horizontally across a floor, considering a coefficient of friction of 0.33 and a pulling angle of 59.9 degrees over a distance of 2.60 m. The original poster seeks to determine the force pulling the box as part of their solution process.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to understand the concept of apparent mass and its relevance to the problem. They explore the relationship between forces acting on the box using free body diagrams and equations of motion. Some participants question the assumptions regarding apparent weight and its calculation, while others suggest alternative interpretations of the normal force.

Discussion Status

The discussion is ongoing, with participants providing insights and alternative assumptions regarding the apparent weight and normal force. There is no explicit consensus yet, but some guidance has been offered regarding the interpretation of apparent weight in relation to the normal force.

Contextual Notes

Participants are navigating the definitions and implications of apparent mass and weight, which may be contributing to confusion in the problem setup. The original poster has expressed uncertainty about their calculations and the relevance of certain concepts.

jmm5180
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Homework Statement


How much work is done by friction when a box with an apparent mass of 325kg moves horizontally across a floor with coefficient of friction of .33 and is pulled at 59.9 degree angle for 2.60 m? What is the force that is pulling the box?

Homework Equations


W=Fdcos@ (@= theta)
Fnet=ma

The Attempt at a Solution


I searched for what apparent mass was, but what I found seemed to do with volume and water displacement, which aren't related to this problem. Instead I tried solving the second question first because I needed Normal force to solve the work done by friction.

For my free body diagram, I had force applied (Fa) in the y direction upwards on the y-axis along with normal force. Along the negative y-axis I had weight. Force of friction (Ff) was along the negative x axis, and force applied in the x direction was on the positive x axis.

In the x direction...
Ff=Facos@ (since no acceleration)
uN = FaCos@

In the y direction...
Fasin@ + N = W (again since no acceleration)
N= mg - FaSin@

So plugging in,,,
u(mg-Fasin@) = FaCos@

Solving for Fa I got...
umg-uFasin@ = Facos@
Fa= umg/(usin@ + cos@)
Fa= (.33*325 kg*9.8)/(.33sin59.9+cos59.9)
Getting that the force applied = 1335.50 N, but this is not correct.

Any help would be appreciated, thanks in advance.
 
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I found this on a Google search:
In physics, apparent weight is a property of objects that corresponds to how heavy an object is. The apparent weight of an object will differ from the weight of an object whenever the force of gravity acting on the object is not balanced by an equal but opposite normal force.
 
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If you assume ##apparent \ weight = mg - N## do you see a way to proceed?
 
anlon said:
If you assume ##apparent \ weight = mg - N## do you see a way to proceed?
Yes, thank you!
 
Try taking the apparent weight = N.
 

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