# Solving Static Problems: Get Started with Hints

• vu10758
In summary, The conversation is about two problems that the speaker is struggling with. The first problem involves the weight of a penguin being supported by a wire, while the second problem involves finding the force in a hinge. The speaker is looking for hints on how to get started on both problems and is confused about the reasoning behind the equations used for problem 14. They also mention not understanding the question for problem 15. Another person offers some advice on how to approach problem 15 by considering the equations of equilibrium. The speaker also expresses dissatisfaction with their answers for problem 14 and questions if they are missing a basic principle.
vu10758
I have no idea on how to start these two problems. I haven't done any work, but please give me some hints on how to get started.

The two problems are here
http://viewmorepics.myspace.com/index.cfm?fuseaction=viewImage&friendID=128765607&imageID=1461065539

For problem 14, the anskwer are 1.2kg, .3kg, and .1kg
for 15, the answers are 54.9N,95N,170N.

For problem 14, I know that the right of the wire extends 3 times as far to suppor the penguin. It appears to me that we divide the mass by four each time with the exception of the last time. What is the reasoing behind it?

For 15, I really have no idea. Maybe it's because I don't really understand the question.

vu10758 said:
For 15, I really have no idea. Maybe it's because I don't really understand the question.

Which part don't you understand?

The force in a hinge has two components - it is convenient to set one of them to be horizontal, and the other vertical. You know the mass of the fence, and you know the tension in the cable. Think about the equations of equilibrium and try to solve the problem.

Take notice that since the hinges are colineal (imagine a vertical line passing through them), you should take advantage that their vertical component won't have moment if you take moment about either of the hinges.

I am not very happy with the answers for 14. For each of the crossbars to be in rotational equilibrium

$$w_l \frac{l}{3} = w_r \frac{2l}{3}$$

which after cancellation comes to

$$m_l = 2m_r$$

where the l and r subscripts refer to the masses hanging from the left and right end of the crossbar. Therefore for the topmost crossbar this comes to

$$2.4 = m_2 + m_3 + m_4$$

or am I missing some basic principle?

## 1. How do I approach solving a static problem?

The first step in solving a static problem is to identify the key variables involved and the known values. Then, draw a free-body diagram to visualize the forces acting on the object. Next, apply Newton's second law and set up equations to solve for the unknown variables.

## 2. What are some common hints for solving static problems?

Some common hints for solving static problems include breaking forces into components, using trigonometry to solve for angles, and considering the equilibrium of forces in both the horizontal and vertical directions.

## 3. How do I know if my solution to a static problem is correct?

To check the correctness of your solution, make sure that it satisfies all the given conditions and equations. Additionally, check if the units of your final answer are correct and if the magnitude and direction of the forces are reasonable.

## 4. What should I do if I am stuck on a static problem?

If you are stuck on a static problem, try approaching it from a different perspective. Break down the problem into smaller, more manageable parts and try solving them individually. You can also consult your textbook or classmates for guidance.

## 5. Can I use a calculator to solve static problems?

Yes, you can use a calculator to solve static problems, especially for more complex equations involving trigonometry or multiple variables. However, it is important to show all the steps of your calculations to receive full credit for your solution.

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