Equilibrium of Forces: Solving for VA and VD in a Statics Problem

In summary, the conversation discusses a problem with finding forces in equilibrium and the solution involves calculating the sum of moments and forces at different points. However, the person's attempt at a solution is incorrect due to missing contributions from certain loads.
  • #1
chetzread
801
1

Homework Statement


I couldn't get the forces in equlibrium in this question

Homework Equations

The Attempt at a Solution


VA + VD = 35(3.5) + 10+15 = 147.5

sum of moment about D = -35(3.5)(1.75+ 3.7) +15(1) + VA(3.5 + 1.7+ 2) = 0
VA = 90.6upwards

Sum of moment about C = -35(3.5)(1.75+1.7) +10(0.7) -VD(2) +15(3) =0
VD = -185 ( downwards) ,

So, VA + VD = -185+ 90.6 = -94.4

So , VA + VD = 90.6 -185 = -94.4N , which is not 147.5N , which part of my working is wrong ?
 

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  • #2
Which part of my working is wrong ?
 
  • #3
chetzread said:

Homework Statement


I couldn't get the forces in equlibrium in this question

Homework Equations

The Attempt at a Solution


VA + VD = 35(3.5) + 10+15 = 147.5
ok
sum of moment about D = -35(3.5)(1.75+ 3.7) +15(1) + VA(3.5 + 1.7+ 2) = 0
VA = 90.6upwards
you forgot the contribution of the 10 kN load at 1.3 m from D
Sum of moment about C = -35(3.5)(1.75+1.7) +10(0.7) -VD(2) +15(3) =0
VD = -185 ( downwards) ,
you forgot he contribution from VA. It's best to sum moments about A.
So, VA + VD = -185+ 90.6 = -94.4

So , VA + VD = 90.6 -185 = -94.4N , which is not 147.5N , which part of my working is wrong ?
see above
 
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Related to Equilibrium of Forces: Solving for VA and VD in a Statics Problem

1. What is equilibrium of forces in a statics problem?

Equilibrium of forces refers to a state in which all the forces acting on an object are balanced and cancel each other out, resulting in a net force of zero. This means that the object is either at rest or moving at a constant velocity.

2. How do you solve for VA and VD in a statics problem?

To solve for VA and VD, you must first draw a free body diagram of the object, which shows all the forces acting on it. Then, you can apply the principles of equilibrium, which state that the sum of all forces in the x-direction and the sum of all forces in the y-direction must equal zero. By setting up and solving these equations, you can determine the values of VA and VD.

3. What are VA and VD in a statics problem?

VA and VD refer to the vertical and horizontal components of the force applied to an object in a statics problem. VA is the vertical component, which acts in the direction perpendicular to the surface or ground, while VD is the horizontal component, which acts parallel to the surface or ground.

4. Why is it important to find equilibrium of forces in a statics problem?

It is important to find equilibrium of forces in a statics problem because it allows us to determine whether an object will remain at rest or move at a constant velocity. This is crucial in engineering and physics, as it helps us understand the stability and balance of structures and objects.

5. What are some real-life applications of solving for VA and VD in statics problems?

Solving for VA and VD in statics problems is used in various real-life applications, such as designing buildings and bridges, calculating the weight distribution in vehicles, and determining the stability of structures during earthquakes and other natural disasters. It is also important in understanding the mechanics of everyday objects, such as furniture and appliances, to ensure their stability and safety.

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