How Do You Calculate Forces in a Supported Bar with Uneven Loads?

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In summary, the conversation discusses a problem involving a bar with a weight of 500 N and an object weighing 1500 N hung from it. The length of the bar is 2 meters and the distance from the end of the bar to the object is 0.8 meters. The conversation also addresses the relationship between the weight of the bar and the forces acting on it.
  • #1
Questions999
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Homework Statement



We have a bar with the weight of 500 N which stands in A and B.In this bar an object which weights 1500 N has been hung.The length of the bar AB is 2 meters and AD is 0.8 meters.Find FA and FB just like in the picture.

http://s1171.photobucket.com/albums/r549/Elaia06/?action=view&current=sdsd.jpg


The Attempt at a Solution



The resultant momentum is zero so

FA*0+1900*0.8+500*1+2*FB=0
But FB in my book is 850 N.This answer does not fit my answer.
 
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  • #2
Elaia06 said:
FA*0+1900*0.8+500*1+2*FB=0
(1) Why 1900?
(2) Distinguish clockwise and counterclockwise moments: they have different signs.
 
  • #3
it is 1900 sorry , I have written it the wrong way in the data.
FA*0-1900*0.8-500*1+2*FB=0
Still FB is not 860..
 
  • #4
Your drawing is not clear enough.
Maybe you make the drawing, take a snapshot and insert image.
 
  • #5
Elaia06 said:
it is 1900 sorry , I have written it the wrong way in the data.
FA*0-1900*0.8-500*1+2*FB=0
Still FB is not 860..
Are you sure? When I solve for FB using your original data (weight of object = 1500N) I get FB = 850 N. Which matches the answer in your book (at least according to your first post).
 
  • #6
i have written it wrong ,i was sleepy last night :P
It should be 860 N, the Fb.
Yes I get 850 N too.The drawing is just like in my book.
 
  • #7
Not related to this exercise :Ah and by the way, If we have a bar with two forces acting in the beginning and the end of it, what is the relationship of the weight of the bar with the forces? I mean, is the distance from a force to the point of weight equal to the distance of the other force with the weight or not?
 
  • #8
Elaia06 said:
Not related to this exercise :Ah and by the way, If we have a bar with two forces acting in the beginning and the end of it, what is the relationship of the weight of the bar with the forces? I mean, is the distance from a force to the point of weight equal to the distance of the other force with the weight or not?
If the bar is uniform, the weight acts at its center. The support forces at each end will (of course) be equidistant from the center.
 
  • #9
what is a uniform bar? Sorry but english is not my native language :P
 
  • #10
Elaia06 said:
what is a uniform bar?
A bar whose weight is evenly distributed along its length.
 
  • #11
Yes this is an uniform bar, thanks :)
 

FAQ: How Do You Calculate Forces in a Supported Bar with Uneven Loads?

What is equilibrum?

Equilibrum refers to the state of a system where opposing forces or influences are balanced, resulting in a stable and unchanging state.

Why is understanding equilibrum important?

Understanding equilibrum is important in many fields of science, such as chemistry, physics, and biology, as it helps us predict and explain how systems will behave under different conditions.

How do you calculate equilibrum?

The calculation of equilibrum depends on the specific system and variables involved. In general, it involves setting the rates of opposing reactions or forces equal to each other and solving for the equilibrium point.

What factors can affect equilibrum?

Several factors can affect equilibrum, including temperature, pressure, concentration, and the presence of catalysts. Changes in these factors can shift the equilibrium point and alter the behavior of the system.

What are some real-world examples of equilibrum?

Some examples of equilibrum in the real world include the exchange of gases in our lungs and the balance of predator and prey populations in an ecosystem. Chemical reactions, such as the dissociation of water, also reach equilibrum when the rates of the forward and reverse reactions are equal.

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