Another static equilibrium question

In summary, the conversation is discussing a physics problem involving finding the reactions at supports A and E. The solution involves calculating the sum of moments on A and using the distance and force components to find the reaction at E. The direction of the support force is also discussed.
  • #1
SteelDirigibl
40
0

Homework Statement


Screenshot2011-02-23at83853AM.png



Homework Equations


M=fd
M= r x F


The Attempt at a Solution



this question really loses me. I'm not sure what exactly it is asking for, much less how to solve it. I am assuming it want's the force on A and E? I suppose I need to find the moment about each point, to help solve, but I can't seem to figure it out. moments have been tripping me up more than they should, and I'm not sure where to go. I doubt I'll get this solved in time to have turned in, but better learned late than never. Where do I go from here?
 
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  • #2
Even if you have no direction as how to solve, you should draw the free body diagram and just write out the statics equations (sum of all forces/moments...) and try them out.

I'm still a student myself but I don't think this question is much of a problem. Anyway, I'll see how I can be more effective. You're right, The question is asking for the reactions at the supports A and E. Let's start with calculating sum of all moments on A. You got P, you got the 4000 [N] force that you need to break it down to its Y and X component. And there's also a reaction in E whose vetor pushing to the opposite direction of the wall. This is your unknown, and you have the distance (3.6)... can you find E from that?
 
  • #3
so, moment about A would be 500*9.2-cos(27)*4000*4.6=-11795 Nm

then we divide that by the distance? (3.6)

and force at F is 3276. Should it be towards the wall (negative) or away (positive)
 
  • #4
Good job! And good question. The support force is pushing against the 4000 [N]...really all the forces in the equaion, including P, are "fighting against" that major force from causing any movement. Think about the "fighting direction" of E. If it wasn't that, that force would jam that structure inside the wall where E is, with A providing its rotation axis.
 
  • #5


As a scientist, it is important to approach problems with a systematic and logical mindset. In this case, the question is asking for the forces on points A and E in a static equilibrium system. To solve this, we can start by drawing a free body diagram of the system and labeling all the known forces and distances. From there, we can use the equations M=fd and M=rxF to calculate the moments about points A and E. By setting these moments equal to zero, we can solve for the unknown forces. It may also be helpful to use the principle of transmissibility, which states that a force acting at any point on a rigid body can be transferred to any other point along its line of action without changing its effect on the body. This can help simplify the problem and make it easier to solve. Additionally, practicing more problems involving moments and static equilibrium can help improve understanding and problem-solving skills in this area. Remember, it is important to approach problems with patience and persistence, and to seek help from resources such as textbooks, classmates, or instructors if needed.
 

1. What is static equilibrium?

Static equilibrium is a state in which all forces acting on an object are balanced, resulting in no net force or acceleration.

2. How is static equilibrium different from dynamic equilibrium?

Static equilibrium involves a stationary object, while dynamic equilibrium involves an object in motion at a constant velocity.

3. What are the conditions for static equilibrium?

The conditions for static equilibrium are that the net force on an object must be zero and the net torque (rotational force) on an object must also be zero. This means that the object is either at rest or moving at a constant velocity.

4. How is static equilibrium used in real life?

Static equilibrium is used in various applications, such as architecture, engineering, and physics. For example, it is used to design structures that can withstand external forces without collapsing or to analyze the forces acting on an object in order to predict its motion.

5. What happens when an object is not in static equilibrium?

If an object is not in static equilibrium, there will be a net force acting on it, causing it to accelerate or move in a certain direction. This can result in the object falling, sliding, or rotating, depending on the direction and magnitude of the net force.

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