Problem about finding the work done by friction force

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Homework Help Overview

The problem involves calculating the work done by the friction force acting on a block being dragged over a horizontal surface. The block has a specified mass, applied force, displacement, and friction force.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster expresses confusion about how to approach the problem, indicating a lack of clarity on the initial steps. Some participants discuss the concept of work done by friction and provide a formula for calculating work, while others suggest recalling fundamental principles related to force and displacement.

Discussion Status

Participants are exploring different aspects of the problem, with some providing guidance on the calculation of work done by friction. There is an acknowledgment of the negative nature of work done by friction, but no consensus has been reached on the overall approach to the problem.

Contextual Notes

The original poster has previously solved a related problem but finds this particular question confusing. There may be assumptions about the understanding of work and forces that are being questioned.

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Homework Statement



A block of mass M=3.4 kg is dragged over a horizontal surface by a force F=20.0 N. The block is displaced a distance d=17.0 m, the friction force Ff is 3.3 N. What is the work done by the friction force?


Homework Equations



Ff=μkFn

The Attempt at a Solution



I solved a problem before this one in finding the applied force but this one is very confusing to me. I have no idea where to even start. Thank you!
 
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Work done by friction is always negative. The work done by a constant force is always the dot product of the force multiplied the displacement whether or not the force is the cause of the displacement. So the work done would be -3.3*17 = -56.1 Joules.
 
Why don't we start with recalling how to calculate the work done by any Force?
[itex]\Large W = \int \vec{F} \cdot d\vec{r}[/itex]
We can reduce this to simply:
[itex] \vec{F}\cdot{\vec{x}}[/itex]
Now the rest is pretty straightforward in your case.
Hope that takes care of the confusion,
Daniel
 
Thank you so much!
 

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