Can't Derive Friction From Equation

In summary, the flight attendant is exerting a force of 40 N and 52.0 degrees horizontal with a constant velocity. The work done by friction is 10 N.
  • #1
interXdragon
13
0
A question that I've spent hours on, but still can't seem to extract friction from it:

10.) A flight attendant pulls her 70.0N flight bag a distance of 253m along a level airport floor a a constant velocity. The force she exerts is 40.0N an angle of 52.0 Degrees horizontal. Find the following
b. the work done by force of friction on the flight bag​
c. the coefficient of kenetic friction between the flight bag and the floor​

Any suggestions?
 
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  • #2
What have you done till now?
 
  • #3
I've figured out A... which asks for the work done by the flight attendant. I've looked up the three friction equations. I've tried solving C by using mu = fmax/fnormal ( mu = 40N / 70N ). And I've put a lot of thought into the two other equations, but they solve for the cofficient itself, which isn't the question.
 
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  • #4
Have you drawn the FBD for the bag and split the components of the force? Also, since the velocity is constant, what can you say about the net sum of the forces along the horizontal direction?
 
  • #5
Yes, I always draw a picture for my hardest questions. At the moment, I don't have a camera to take a picture of my work, however, I've created a little picture that imitates the work on my paper. Here it goes:
http://unityofthedragons.org/ex.jpg [Broken]

This doens't include my answers because I kinda rushed to do this picture. However, the idea is there. Thanks a lot for helping please correct me if I'm wrong.
 
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  • #6
You should include all the forces in your FBD. That includes the normal force from the ground and the force due to friction. Can you post and show the equations you get?
 
  • #7
yes, please give me sometime
 
  • #8
Okay, here you go, this includes the friction equations:

http://unityofthedragons.org/ex.jpg [Broken]
 
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  • #9
Why does static friction come into play here? The block is moving, so only kinetic friction will exist. And that will be [tex] \mu_k N [/tex].
The value of the Normal force is not [tex] mg [/tex].
You should write the components of the 40 N force along the horizontal and vertical direction. Once you do that, you can calculate the normal force.
 
  • #10
I understand now, thanks for all your help, siddharth!
 

1. What does the equation for friction represent?

The equation for friction represents the relationship between the force of friction and the normal force exerted on an object. It is used to calculate the force of friction acting on an object in a given situation.

2. Why can't friction be derived from an equation?

Friction is a complex phenomenon that is influenced by a variety of factors, including surface roughness, temperature, and velocity. Therefore, it cannot be derived from a single equation, but rather requires multiple equations and models to accurately describe its behavior.

3. How is the equation for friction determined?

The equation for friction is determined through experiments and observations of the behavior of objects in various situations. By collecting data and analyzing the relationship between the force of friction and other variables, scientists can develop equations that accurately describe friction.

4. Can the equation for friction be used in all situations?

No, the equation for friction is a simplified model that is only applicable in certain situations. For example, it does not take into account factors such as air resistance or the type of surface the object is moving on. In these cases, more complex equations or models may be needed.

5. How can the equation for friction be improved?

Scientists are constantly working to improve the equations and models used to describe friction. This can involve incorporating new factors, refining existing equations, and developing more accurate experimental methods. Ongoing research in this area helps to improve our understanding of friction and its effects on objects in motion.

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