Solving Simple Statics Problem - Find Force Fb & Fa

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In summary, the speaker is asking for help with a simple statics problem involving a bar with a length of Z from point A to point B and a torque input at point C. They are having trouble with the sum of forces and moments and are looking for assistance in converting the torque to a force and finding the correct sum of forces in one direction. They have tried taking the sum of moments about each end (A and B), but are still struggling.
  • #1
todd8541
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Guys
I need some help with a simple statics problem.

I have a bar with a length of Z from point A to point B. A torque is input at point c which is located a length of Y from point A. There are two reaction forces: Fb located at Point B and Fa located at point A. no other forces are input. I am having problems doing my sum of forces and moments.

I know for zero rotation the sum of moments is at point c
T=Fb(Z-Y) + Fa(Y)

However, I can't seem to find the correct sum of forces in one direction let's just say x.

With the sum of forces I get FB = FA I know this isn't true because they are two different distances from Point C and there will have different magnatudes. any help would be appreciated.

I am thinking I need to some how convert T to a force with some sort of ratios of the lengths. any assistance would be appreciated.

I can't believe this simple of a problem is kicking my butt.

Thanks
 
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  • #2
Try doing the sum of the moments about each end (A and B). About point A, there is no moment due to Fa and then you only have the moment around C and then the moment caused by Fb a distance of Z units away. You solve for Fb. Repeat the process for Fa, but take the moment about point B.

Hope this helps.
 

Related to Solving Simple Statics Problem - Find Force Fb & Fa

1. How do I identify the forces acting on the object in a statics problem?

In order to find the forces Fb and Fa, you need to first identify all the forces acting on the object. This can be done by drawing a free-body diagram and labeling all the forces, including external forces (such as gravity or applied forces) and internal forces (such as tension or compression).

2. What is the difference between a statics problem and a dynamics problem?

A statics problem deals with objects that are in equilibrium, meaning they are not moving or accelerating. In a dynamics problem, the object is in motion and may be accelerating. This difference is important because it affects how you approach and solve the problem.

3. How do I determine the direction of the forces in a statics problem?

The direction of the forces can be determined by looking at the free-body diagram and using the right-hand rule. Point your thumb in the direction of the force and your fingers will curl in the direction of the positive rotation. Alternatively, you can use vector components to break down the forces into x and y components.

4. What equations should I use to solve for Fb and Fa in a statics problem?

To solve for Fb and Fa, you can use Newton's second law (ΣF = ma) or the principle of moments (ΣM = 0). In some cases, you may need to use both equations to find a solution. It is important to carefully analyze the problem and determine which equations are most appropriate to use.

5. How can I check my answer to make sure it is correct?

One way to check your answer is by using a force table or a force calculator. These tools allow you to input the forces and their corresponding angles, and they will calculate the net force and direction. Another way is to use the equations again with your calculated values to see if they balance out. It is always a good idea to double-check your work to ensure accuracy.

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