Engineering Statics Question

In summary, a student has posted a question with an image showing a physics problem with three forces acting on an object at different angles. They have attempted to solve the problem but are unsure of their answer and why the question does not specify the direction of the resultant force. Another user has pointed out a possible error in their calculations and suggests using trigonometry to solve for the unknowns. The conversation ends with the user summarizing the known and unknown variables in the problem.
  • #1
1
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Homework Statement



http://imgur.com/a/FyekZ
I took the liberty of uploading everything. The first picture is the question, while the other two is my attempt at answering it in two parts. What I do not understand is what I did wrong or where I went wrong.
I also would like to know why, unlike many other questions from the text, this question does not specify in which direction the resultant force is directed. Is the question wrong, or am I supposed to go about this in a different manner?

EDIT: If you cannot see the full image, please click the gear icon (top right of each image - gear appears when you have the mouse over the image) and select view full resolution.

Homework Equations



See above.

The Attempt at a Solution



Please see above.
 
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  • #2
Deleted.
 
Last edited:
  • #3
Ok so there appears to be too many unknowns unless you assume the resulting force is to be in the "u" direction.
 
  • #4
I think you may have made an error in the calc for Fry. Did you forgot to divide by Sin(28)?
 
  • #5
Actually it looks like you can calculate the angle of the resultant. Call that β then..

In x..

FR*Cos(β) = F1*Cos(θ) - F2*3/5 + F3*Cos(45)
so
F1*Cos(θ) = FR*Cos(β) + F2*3/5 - F3*Cos(45) ...(1)

In y..

FR*Sin(β) = F1*Sin(θ) + F2*4/5 - F3*Sin(45)
so
F1*Sin(θ) = FR*Sin(β) - F2*4/5 + F3*Sin(45)...(2)


Knowns F2, F3, FR, θ
Unknowns F1 and β

We have two equations and two unknowns.
 

1. What is Engineering Statics?

Engineering Statics is a branch of engineering mechanics that deals with the study of objects at rest or in constant motion. It involves analyzing the forces acting on a body and determining its equilibrium state.

2. Why is Engineering Statics important?

Engineering Statics is important because it helps engineers to design and build structures that are stable and can withstand external forces. It is also crucial for understanding the behavior of machines and structures under different loading conditions.

3. What are the key principles of Engineering Statics?

The key principles of Engineering Statics include the concept of equilibrium, which states that the net force and net moment acting on a body must be zero for it to be in a state of rest or constant motion. Other principles include the resolution and composition of forces, moments, and the use of free body diagrams.

4. What are some common applications of Engineering Statics?

Engineering Statics has a wide range of applications, including the design and analysis of bridges, buildings, dams, and other structures. It is also used in the design of various mechanical systems, such as car engines, cranes, and aircraft wings.

5. How can I improve my understanding of Engineering Statics?

To improve your understanding of Engineering Statics, it is essential to practice solving problems and working through examples. It can also be helpful to visualize the concepts using diagrams and real-life examples. Additionally, seeking guidance from a tutor or attending review sessions can also aid in improving your understanding of the subject.

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