Calculate resultants of two forces

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In summary, the conversation is discussing how to find the resultant of two forces acting at different points. The question asks for a replacement of the two forces with one force that has the same effect. The solution involves understanding the effect of each force and finding their resultant along the same line. Point A is mentioned as a key point in determining the solution.
  • #1
zeralda21
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Homework Statement



Where does the resultant of the two forces act?

http://i.imgur.com/CBO8fi2.jpg

Homework Equations



None really. Basic algebra for calculating resultants.

The Attempt at a Solution



First off, I have tried to calculate the x and y components of the resultant, call it R. Here I think that R_{x}=0 (both forces are vertical) and R_{y}=-20 (net force in the y-direction). So the resultant is:

R=R_{x}+R_(y} = 0x-20y with magnitude of 20N. However, I am unable to understand how the lengths will help me.
 
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  • #2
The question wants you to replace the two forces at different distances with one force that has the same effect. So - what is the effect of each force as drawn? (Hint: what is special about point A?)
 
  • #3
Simon Bridge said:
The question wants you to replace the two forces at different distances with one force that has the same effect. So - what is the effect of each force as drawn? (Hint: what is special about point A?)

That is what I have tried to do actually. I have replaced them with one downward force with magnitude 20N. But I don't know where it is located.

What is special about point A? Well, not sure. There must be a force to compensate the downward force but that is done by the beam(object).
 
  • #4
20N is what you'd get if the forces acted along the same line.
Do they?

Won't each of the two forces create a moment about point A?
 
  • #5
Simon Bridge said:
20N is what you'd get if the forces acted along the same line.
Do they?

Won't each of the two forces create a moment about point A?

Yes, I suppose. I will have to think a little bit about this one before I answer. Not sure about the theory yet.
 

1. What is a resultant force?

A resultant force is the single force that has the same effect as two or more forces acting on an object. It is the combined effect of all the forces acting on an object.

2. How do you calculate resultant force?

To calculate the resultant force, you need to find the vector sum of all the forces acting on an object. This can be done by adding the individual components of the forces in the x, y, and z directions using trigonometric functions.

3. Can the resultant force be negative?

Yes, the resultant force can be negative if the forces acting on an object are in opposite directions or have different magnitudes. A negative resultant force indicates that the object is experiencing a net force in the opposite direction of its motion.

4. How does the angle of the forces affect the resultant force?

The angle between the forces affects the magnitude and direction of the resultant force. If the forces are acting in the same direction, the resultant force will have a larger magnitude. If they are acting in opposite directions, the resultant force will have a smaller magnitude. The direction of the resultant force is determined by the angle between the forces.

5. What is the difference between a balanced and unbalanced resultant force?

A balanced resultant force occurs when the vector sum of all the forces acting on an object is equal to zero. This means that the object will remain at rest or continue moving at a constant velocity. An unbalanced resultant force occurs when the vector sum of the forces is not equal to zero, causing the object to accelerate in the direction of the resultant force.

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