Statics: Finding the moment on point B?

In summary, the problem is asking for the moment about point B of three forces acting on a beam. The equations used are M = F*d⊥, with F representing the force and d⊥ representing the perpendicular distance from the force to point B. The components for each force are calculated, and their perpendicular distances are found by using the right hand method and measuring the distances below the beam. The perpendicular distances for each force are 19ft for F1, 0.5ft for F2, and 11ft for F3.
  • #1
Vanessa Avila
94
1

Homework Statement


fTJnj42.jpg
[/B]
Determine the moment about point B of each of the three forces acting on the beam.

Homework Equations


M = F*d⊥

The Attempt at a Solution


I went and found the components for each of the forces. Please double check it if I did them right:

F1 :
Fx = 0
Fy = 375 lb

F2:

Fx = -500(3/5)lb = -300lb
Fy = -500(4/5)lb = -400lb

F3:
Fx = 160cos30° = 138.6lb
Fy = -160sin30° = -80lb

If those components are right, I'm having trouble finding their perpendicular distances.
 
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  • #2
Based on the figure above is the
F*d⊥ for each of the forces are (without the sign convention/right hand method applied):
F1
Fx1 = 0
Fy1 = 375lb*19ft

F2
Fx2 = -300lb(0.5ft)
Fy2 = -400lb(19ft)

F3
Fx3 = 138.6lb(0.5ft)
Fx3 = -80lb(19ft)

I got 19ft by adding the three dimensions below the beam. Is that correct?
 
  • #3
Label forces with F, and moments (force times distance) with M.
To calculate the moment of force F1 about point B, how far is F1 from point B?
 
  • #4
David Lewis said:
Label forces with F, and moments (force times distance) with M.
To calculate the moment of force F1 about point B, how far is F1 from point B?
Ahh! 11 ft!
 

Related to Statics: Finding the moment on point B?

1. What is statics and how does it relate to finding the moment on point B?

Statics is the branch of mechanics that deals with objects at rest or in constant motion. It is used to analyze the forces acting on a stationary object and determine the equilibrium condition. Finding the moment on point B is a common problem in statics, where we calculate the rotational force acting on a specific point in a system.

2. What is a moment and how is it different from force?

A moment is the product of a force and the perpendicular distance from the point of rotation to the line of action of the force. It is a rotational force that causes an object to rotate around a fixed point. Unlike force, which is a linear force that causes an object to move in a straight line, a moment causes an object to rotate.

3. How do you calculate the moment on point B?

To calculate the moment on point B, you need to first identify the forces acting on the system and their respective distances to point B. Then, you can use the formula: moment = force x distance. Make sure to take into account the direction of the force and the direction of rotation to get the correct sign for the moment.

4. What are some real-life applications of finding the moment on point B?

Finding the moment on point B is a crucial step in designing and analyzing structures, such as buildings, bridges, and machinery. It helps engineers and architects determine if a structure is stable and can withstand the forces acting on it. It is also used in the fields of biomechanics and physics to understand the forces and movements of the human body and other objects.

5. What are some tips for solving problems involving finding the moment on point B?

Here are some tips for solving problems involving finding the moment on point B:

  • Draw a clear and accurate diagram of the system with all the forces labeled and their distances to point B marked.
  • Use the right-hand rule to determine the direction of rotation.
  • Be consistent with units and conversions.
  • Double-check your calculations and make sure to include the correct sign for the moment.

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