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Other High School , General Education

Listen: we know homework isn’t fun, but it is a good way to reinforce the ideas and concepts you’ve learned in class. But what if you’re really struggling with your homework assignments?

If you’ve looked online for a little extra help with your take-home assignments, you’ve probably stumbled across websites claiming to provide the homework help and answers students need to succeed . But can homework help sites really make a difference? And if so, which are the best homework help websites you can use? 

Below, we answer these questions and more about homework help websites–free and paid. We’ll go over: 

• The basics of homework help websites
• The cost of homework help websites 
• The five best homework websites out there 
• The pros and cons of using these websites for homework help 
• The line between “learning” and “cheating” when using online homework help 
• Tips for getting the most out of a homework help website

So let’s get started! 

The Basics About Homework Help Websites–Free and Paid

Homework help websites are designed to help you complete your homework assignments, plain and simple. 

What Makes a Homework Help Site Worth Using

Most of the best sites allow users to ask questions and then provide an answer (or multiple possible answers) and explanation in seconds. In some instances, you can even send a photo of a particular assignment or problem instead of typing the whole thing out! 

Homework help sites also offer more than just help answering homework questions. Common services provided are Q&A with experts, educational videos, lectures, practice tests and quizzes, learning modules, math solving tools, and proofreading help. Homework help sites can also provide textbook solutions (i.e. answers to problems in tons of different textbooks your school might be using), one-on-one tutoring, and peer-to-peer platforms that allow you to discuss subjects you’re learning about with your fellow students. 

And best of all, nearly all of them offer their services 24/7, including tutoring! 

What You Should Should Look Out For

When it comes to homework help, there are lots–and we mean lots –of scam sites out there willing to prey on desperate students. Before you sign up for any service, make sure you read reviews to ensure you’re working with a legitimate company. 

A word to the wise: the more a company advertises help that veers into the territory of cheating, the more likely it is to be a scam. The best homework help websites are going to help you learn the concepts you’ll need to successfully complete your homework on your own. (We’ll go over the difference between “homework help” and “cheating” a little later!) 

You don't need a golden piggy bank to use homework help websites. Some provide low or no cost help for students like you!

How Expensive Are the Best Homework Help Websites?

First of all, just because a homework help site costs money doesn’t mean it’s a good service. Likewise, just because a homework help website is free doesn’t mean the help isn’t high quality. To find the best websites, you have to take a close look at the quality and types of information they provide! 

When it comes to paid homework help services, the prices vary pretty widely depending on the amount of services you want to subscribe to. Subscriptions can cost anywhere from $2 to $150 dollars per month, with the most expensive services offering several hours of one-on-one tutoring with a subject expert per month.

The 5 Best Homework Help Websites 

So, what is the best homework help website you can use? The answer is that it depends on what you need help with. 

The best homework help websites are the ones that are reliable and help you learn the material. They don’t just provide answers to homework questions–they actually help you learn the material. 

That’s why we’ve broken down our favorite websites into categories based on who they’re best for . For instance, the best website for people struggling with math might not work for someone who needs a little extra help with science, and vice versa. 

Keep reading to find the best homework help website for you! 

Best Free Homework Help Site: Khan Academy

• Price: Free!
• Best for: Practicing tough material 

Not only is Khan Academy free, but it’s full of information and can be personalized to suit your needs. When you set up your account , you choose which courses you need to study, and Khan Academy sets up a personal dashboard of instructional videos, practice exercises, and quizzes –with both correct and incorrect answer explanations–so you can learn at your own pace. 

As an added bonus, it covers more course topics than many other homework help sites, including several AP classes.

Runner Up: Brainly.com offers a free service that allows you to type in questions and get answers and explanations from experts. The downside is that you’re limited to two answers per question and have to watch ads. 

Best Paid Homework Help Site: Chegg

• Price: $14.95 to $19.95 per month
• Best for: 24/7 homework assistance  

This service has three main parts . The first is Chegg Study, which includes textbook solutions, Q&A with subject experts, flashcards, video explanations, a math solver, and writing help. The resources are thorough, and reviewers state that Chegg answers homework questions quickly and accurately no matter when you submit them.  

Chegg also offers textbook rentals for students who need access to textbooks outside of their classroom. Finally, Chegg offers Internship and Career Advice for students who are preparing to graduate and may need a little extra help with the transition out of high school. 

Another great feature Chegg provides is a selection of free articles geared towards helping with general life skills, like coping with stress and saving money. Chegg’s learning modules are comprehensive, and they feature solutions to the problems in tons of different textbooks in a wide variety of subjects. 

Runner Up: Bartleby offers basically the same services as Chegg for $14.99 per month. The reason it didn’t rank as the best is based on customer reviews that say user questions aren’t answered quite as quickly on this site as on Chegg. Otherwise, this is also a solid choice!

Best Site for Math Homework Help: Photomath

• Price: Free (or $59.99 per year for premium services) 
• Best for: Explaining solutions to math problems

This site allows you to t ake a picture of a math problem, and instantly pulls up a step-by-step solution, as well as a detailed explanation of the concept. Photomath also includes animated videos that break down mathematical concepts to help you better understand and remember them. 

The basic service is free, but for an additional fee you can get extra study tools and learn additional strategies for solving common math problems.

Runner Up: KhanAcademy offers in-depth tutorials that cover complex math topics for free, but you won’t get the same tailored help (and answers!) that Photomath offers. 

Best Site for English Homework Help: Princeton Review Academic Tutoring

• Price: $40 to $153 per month, depending on how many hours of tutoring you want 
• Best for: Comprehensive and personalized reading and writing help 

While sites like Grammarly and Sparknotes help you by either proofreading what you write via an algorithm or providing book summaries, Princeton Review’s tutors provide in-depth help with vocabulary, literature, essay writing and development, proofreading, and reading comprehension. And unlike other services, you’ll have the chance to work with a real person to get help. 

The best part is that you can get on-demand English (and ESL) tutoring from experts 24/7. That means you can get help whenever you need it, even if you’re pulling an all-nighter! 

This is by far the most expensive homework site on this list, so you’ll need to really think about what you need out of a homework help website before you commit. One added benefit is that the subscription covers over 80 other subjects, including AP classes, which can make it a good value if you need lots of help!  

Best Site for STEM Homework Help: Studypool

• Best for: Science homework help
• Price: Varies; you’ll pay for each question you submit

When it comes to science homework help, there aren’t a ton of great resources out there. The best of the bunch is Studypool, and while it has great reviews, there are some downsides as well. 

Let’s start with the good stuff. Studypool offers an interesting twist on the homework help formula. After you create a free account, you can submit your homework help questions, and tutors will submit bids to answer your questions. You’ll be able to select the tutor–and price point–that works for you, then you’ll pay to have your homework question answered. You can also pay a small fee to access notes, lectures, and other documents that top tutors have uploaded. 

The downside to Studypool is that the pricing is not transparent . There’s no way to plan for how much your homework help will cost, especially if you have lots of questions! Additionally, it’s not clear how tutors are selected, so you’ll need to be cautious when you choose who you’d like to answer your homework questions.  

What Are the Pros and Cons of Using Homework Help Sites?

Homework help websites can be a great resource if you’re struggling in a subject, or even if you just want to make sure that you’re really learning and understanding topics and ideas that you’re interested in. But, there are some possible drawbacks if you don’t use these sites responsibly. 

We’ll go over the good–and the not-so-good–aspects of getting online homework help below. 

3 Pros of Using Homework Help Websites 

First, let’s take a look at the benefits. 

#1: Better Grades Beyond Homework

This is a big one! Getting outside help with your studies can improve your understanding of concepts that you’re learning, which translates into better grades when you take tests or write essays. 

Remember: homework is designed to help reinforce the concepts you learned in class. If you just get easy answers without learning the material behind the problems, you may not have the tools you need to be successful on your class exams…or even standardized tests you’ll need to take for college. 

#2: Convenience

One of the main reasons that online homework help is appealing is because it’s flexible and convenient. You don’t have to go to a specific tutoring center while they’re open or stay after school to speak with your teacher. Instead, you can access helpful resources wherever you can access the internet, whenever you need them.

This is especially true if you tend to study at off hours because of your extracurriculars, work schedule, or family obligations. Sites that offer 24/7 tutoring can give you the extra help you need if you can’t access the free resources that are available at your school. 

#3: Variety

Not everyone learns the same way. Maybe you’re more of a visual learner, but your teacher mostly does lectures. Or maybe you learn best by listening and taking notes, but you’re expected to learn something just from reading the textbook . 

One of the best things about online homework help is that it comes in a variety of forms. The best homework help sites offer resources for all types of learners, including videos, practice activities, and even one-on-one discussions with real-life experts. 

This variety can also be a good thing if you just don’t really resonate with the way a concept is being explained (looking at you, math textbooks!).

Not so fast. There are cons to homework help websites, too. Get to know them below!

3 Cons of Using Homework Help Websites 

Now, let’s take a look at the drawbacks of online homework help. 

#1: Unreliable Info

This can be a real problem. In addition to all the really good homework help sites, there are a whole lot of disreputable or unreliable sites out there. The fact of the matter is that some homework help sites don’t necessarily hire people who are experts in the subjects they’re talking about. In those cases, you may not be getting the accurate, up-to-date, and thorough information you need.

Additionally, even the great sites may not be able to answer all of your homework questions. This is especially true if the site uses an algorithm or chatbot to help students…or if you’re enrolled in an advanced or college-level course. In these cases, working with your teacher or school-provided tutors are probably your best option. 

#2: No Clarification

This depends on the service you use, of course. But the majority of them provide free or low-cost help through pre-recorded videos. Watching videos or reading info online can definitely help you with your homework… but you can’t ask questions or get immediate feedback if you need it .

#3: Potential For Scamming 

Like we mentioned earlier, there are a lot of homework help websites out there, and lots of them are scams. The review comments we read covered everything from outdated or wrong information, to misleading claims about the help provided, to not allowing people to cancel their service after signing up. 

No matter which site you choose to use, make sure you research and read reviews before you sign up–especially if it’s a paid service! 

When Does “Help” Become “Cheating”?

Admittedly, whether using homework help websites constitutes cheating is a bit of a grey area. For instance, is it “help” when a friend reads your essay for history class and corrects your grammar, or is it “cheating”? The truth is, not everyone agrees on when “help” crosses the line into “cheating .” When in doubt, it can be a good idea to check with your teacher to see what they think about a particular type of help you want to get. 

That said, a general rule of thumb to keep in mind is to make sure that the assignment you turn in for credit is authentically yours . It needs to demonstrate your own thoughts and your own current abilities. Remember: the point of every homework assignment is to 1) help you learn something, and 2) show what you’ve learned. 

So if a service answers questions or writes essays for you, there’s a good chance using it constitutes cheating. 

Here’s an example that might help clarify the difference for you. Brainstorming essay ideas with others or looking online for inspiration is “help” as long as you write the essay yourself. Having someone read it and give you feedback about what you need to change is also help, provided you’re the one that makes the changes later. 

But copying all or part of an essay you find online or having someone write (or rewrite) the whole thing for you would be “cheating.” The same is true for other subjects. Ultimately, if you’re not generating your own work or your own answers, it’s probably cheating.

5 Tips for Finding the Best Homework Help Websites for You

Now that you know some of our favorite homework help websites, free and paid, you can start doing some additional research on your own to decide which services might work best for you! Here are some top tips for choosing a homework help website. 

Tip 1: Decide How You Learn Best 

Before you decide which site or sites you’re going to use for homework help, y ou should figure out what kind of learning style works for you the most. Are you a visual learner? Then choose a site that uses lots of videos to help explain concepts. If you know you learn best by actually doing tasks, choose a site that provides lots of practice exercises.

Tip 2: Determine Which Subjects You Need Help With

Just because a homework help site is good overall doesn’t mean that it’s equally good for every subject. If you only need help in math, choose a site that specializes in that area. But if history is where you’re struggling, a site that specializes in math won’t be much help. So make sure to choose a site that you know provides high-quality help in the areas you need it most. 

Tip 3: Decide How Much One-On-One Help You Need 

This is really about cost-effectiveness. If you learn well on your own by reading and watching videos, a free site like Khan Academy is a good choice. But if you need actual tutoring, or to be able to ask questions and get personalized answers from experts, a paid site that provides that kind of service may be a better option.

Tip 4: Set a Budget

If you decide you want to go with a paid homework help website, set a budget first . The prices for sites vary wildly, and the cost to use them can add up quick. 

Tip 5: Read the Reviews

Finally, it’s always a good idea to read actual reviews written by the people using these homework sites. You’ll learn the good, the bad, and the ugly of what the users’ experiences have been. This is especially true if you intend to subscribe to a paid service. You’ll want to make sure that users think it’s worth the price overall!

What’s Next?

If you want to get good grades on your homework, it’s a good idea to learn how to tackle it strategically. Our expert tips will help you get the most out of each assignment…and boost your grades in the process.

Doing well on homework assignments is just one part of getting good grades. We’ll teach you everything you need to know about getting great grades in high school in this article.

Of course, test grades can make or break your GPA, too. Here are 17 expert tips that’ll help you get the most out of your study prep before you take an exam.

Ashley Sufflé Robinson has a Ph.D. in 19th Century English Literature. As a content writer for PrepScholar, Ashley is passionate about giving college-bound students the in-depth information they need to get into the school of their dreams.

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Every one of our homework helpers cares about your success as a student. Each member of our team has lots of work experience and education that make them qualified to provide homework help. Some of our team members even have advanced degrees such as PhDs. Online homework solvers must also go through lots of steps to get hired here. We perform assessments to make sure they are truly up to the task! We hire a wide array of subject matter experts to help with lots of different types of homework assignments. In addition, we focus on the needs of our customers to make sure they keep coming back. After using our service, you’re guaranteed to feel great about our service. Also, we know students worry about meeting certain deadlines so we always provide help promptly. You will receive your assignment by your requested deadline, always. All of these reasons are why students like you continue to use our online homework helpers to get great assignment grades. Give us a try to see for yourself. We guarantee you will not be let down by our amazing homework helpers.

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ME 274: Basic Mechanics II

Homework h6.j - sp24.

DISCUSSION THREAD

Question : Can you tell from the animation if the excitation frequency ω  is smaller than or larger than the natural frequency ω n of the system?

Any questions?? Please ask/answer questions regarding this homework problem through the "Leave a Comment" link above.

91 thoughts on “Homework H6.J - Sp24”

For the acceleration of Block C do we add the accelerations that are contributed by A and B?

Yes I believe you would add the friction forces from each disk for the sum of forces in the x for C.

Instead of adding the accelerations I would recommend using the rigid body equations to relate the acceleration of C to the accelerations of A and B separately, giving you two more equations to work with.

In the FBD do you assumer there are two normal forces? One between the ground and the disks, and another on the top the the disk that contacts with the bar?

Yes, but these normal forces end up cancelling due to taking the moment of the discs.

What is the best approach? To use three FBDs of the disks and bar or one big FBD of everything?

The best approach in my opinion is 3 separate FBDs it makes the question easier overall. It helps you look at them separately and determine the best approach. In terms of moments and force equations. As well as being able to take moments across the two contact points of the disk are easier if you use two separate disk FBDs.

If you use a FDB of everything it will make looking at the problem difficult. And youll need to account for the reactionary forces if you choose to do a single system and the frictional forces.

I also used three separate FBDs, as I was able to better asses each individual component to understand my next steps.

Yes, you do assume that since they are making contact with both surfaces

I would think so. I drew them on my FBD.

In what direction is the friction on the no slip points facing? I’m having issues understanding the relationship between the point of contact with the ground and the point with the bar C.

I always like to think of friction as opposing motion. I like to think about which way the point would move if it were able to slide without friction. Then friction acts in the opposite direction of that.

This gets kind of tricky when there is a no slip point though as the direction which the disk rolls is typically the direction that the friction force acts due to the nature of no slip points.

I believe as long as the frictions corresponding to the two different components that form a no slip point are equal and opposite in sign, the direction does not matter.

Whenever I try to draw FBDs with friction and a rotating disk, I draw the arrow representing the direction of the friction so that it points at the arrow representing the direction the wheel rotates. The two arrowheads meet. This is the strategy that works best for me and helps me avoid negative numbers. The friction acting on either surface would point in the opposite direction of the friction at the corresponding contact point on the wheel.

When I change the theta double dot for A and B into X double dot and plug that back in with the numbers my X double dot cancels, I don't fell like that's right but my process up that point feels ok. Is this right or did I make a mistake?

You should get the angular acceleration of A and B in terms of linear acceleration. If you have these relations correct it is possible you substituted angular acceleration for linear acceleration. The problem asks for the EOM in terms of x so you would need to substitute once again using that relation to get your variables in terms of x and not angular terms.

The x double dot did not cancel in my equation. I got an x double dot term in both the moments about A and B from their contact points with the ground that did not cancel.

Instead of taking the moment around the center of the disks, if you take the moment around the bottom of the disk, you're able to only have to deal with 2 friction forces, not 4.

The way I approached this problem is taking a moment about c for both disks and doing a sum of forces for the frictions on the bar.

In this system, analyzing the differential equation of motion is important to understanding its behavior. By deriving the equation and considering the forced response amplitude, you can gain insights into how external forces affect the system's dynamics.

I am still not understanding the direction of friction between the block and the top of the disc. Could someone explain?

The direction for the friction forces that you choose on the block is arbitrary. If you draw equal and opposite forces on the two disks you will be OK. As long as you do not set friction = mu*normal force, friction is a standard reaction force. Choose a direction and be consistent throughout, and signs take care of themselves.

During half of the cycle of oscillation, the friction force will point to the left, and during the other half it will point to the left. The math will take care of that if you are consistent throughout with your FBDs and sign conventions.

For his problem I recommend the following: Check out problem 6.A.3 in case that you have issues with how the friction is supposed to be placed on the system, and make sure that your coordinate systems are consistent so that whenever you transform everything back to X coordinate it's easy to do so.

I have found that the easiest way for me to understand and break down the system is if I align the friction arrow with the wheel's rotation direction, meeting at the arrowhead. However, the direction of the friction can be random, and as long as you are careful with your signs, you should get the same results.

This keeps confusing me to be honest. I know that the direction of friction force should be opposing motion, but given that the motion changes as a function of time I dont really understand which direction to put the friction force in when drawing the FBDs and setting up the equaitons.

Taking the moment about the non-slip points can help reduce the complexity of the resulting equations, as long as the parallel axis theorem is used. Aside from that, being careful with signs and directions is important, drawing multiple FBDs is important and can help generate equations.

If you take the moment from the center of the circle, there will 4 friction variables to deal with instead of two. It leads to having to add a bunch of different equations together to cancel out the friction terms which is very tedious. If I were to do this problem again, I would recommend taking the moment from the bottom no slip point so that only two friction forces would have to be dealt with. Also, keep in mind to differentiate the thetas of each disk since their radius is different.

Remember to rewrite the x-components of the EOM in terms of theta to get the kinetic and potential aspects of the equation in terms of theta and its derivatives.

Does the "forced response" of a system always only include the particular solution of the differential equation of motion by definition? By the setup of the problem, it the particular and complementary solutions have different angular velocities, so it would get tricky to combine the sin/cos terms to reach a single amplitude.

That's correct. The particular solution is from f(t) which is called the "forced response" of the system in the lecturebook. This external forcing term causes the response to be a certain frequency.

I have set up three equations -- 2 moments about no-slip points and a sum of forces in the x direction for the block. However, I need f(t) to solve these equations for the friction forces, and I don't know what w is. Can someone help me?

It sounds like you are on the right track. You should be able to keep w as a variable until part B. Try to replace the friction forces in your net force of the block equations by solving for the friction in the moment equations.

Yes solving for friction with moment equations will give you more equations to simultaneously solve and match up the unknowns

w is given in part b of the find statement. It says "determine the amplitude of the forced response of block C when w is one-half the natural frequency of the system." Calculate the natural frequency using your EOM and then halve it.

To find the amplitude, the particular solution is useful when you take the absolute value because the sin term cancels out and you are just left with B.

I found it easiest to take moment about the center of the disks. Additionally, along with the moment, I also summed the forces in the x-direction.

Initially, this problem seemed very daunting due to the four friction forces acting in the system, but taking the moments about the point where the disks make contact with the ground simplified things a lot for me.

I found it pretty useful doing 3 separate FBD's of both disks and the bar. This allows you to set up a newton eq for the bar containing the frictions due to the disks, then setting up euler eq about the IC of both disks.

This is the same way I solved the problem. Taking advantage of the clear four step plan to break the problem down and then solving your resulting equations using a system of equations and taking advantage of the initial conditions.

Remember for Newton/Euler you always want to do individual FBDs instead of one large one. When doing the moments I made sure to assign positive theta in the CCW direction to avoid having negative signs during the kinematics step.

Would we need to have a different set of kinematics? one for each disk?

I took a moments for each of the disks about the contact points with the ground.

I had different Newton Euler Equations from the FBD and general kinematic equations!

I have set-up the kinetic and rigid body equations. How do I go about finding each of the friction forces?

I took moments for each of the disks about their contact points with the ground and I was able to solve for friction.

Try taking the moments of the disks, this will give you more equations to simultaneously solve

For this problem, example 6.A.3 is extremely useful in understanding how to set up the free body diagrams. Make sure to do an individual FBD for each of the disks and the block. This allows you to set up multiple equations to solve for the friction between each disk and the block.

One big hint is to take the moment of the disks around the non-slip contact point. This will allow for the normal forces to not have any affect, which will help simplify the equations.

Be careful about the signs of the friction forces when relating the block to the disks. I had the wrong relationship at first and it threw off the rest of my calculations.

By creating 3 Free Body Diagrams and taking moments around the contact points of the disks, it greatly reduces the amount of calculations nessasary for the problem. This is due to the problem specifying that these points do not slip against the surface.

For the question asked in the hints above ("Can you tell from the animation if the excitation frequency ω is smaller than or larger than the natural frequency ωn of the system?"), I believe that the diagram indicates that the excitation frequency is smaller than the natural frequency. This is because, as in the discussion on HW 6.J, as the disk moves to the left, the force is to the left.

Will I need a separate coordinate system for each disk?

Yes you would use different values to show the coordinates for each, and you would be able to define them in terms of theta.

Yes, this will make it easier to relate theta to X when it comes to solving.

In this question, it is really important to make sure that your signs are correct. In your FBDs, make careful note to draw your signs equal and opposite for forces that are found on more than one component. Besides that, taking moments around the no slip points on the disc and summing the forces on the bar should give you 3 eqns with 3 unknowns, and you can derive the EOM.

By taking the moment about each disk on a contact point, it allows us to eliminate two of the friction forces in our equations, making the solution much easier.

example problem 6c4 and 6c6 helped me figure out how to approach this problem super well.

Remembering that the disks are no slip on both contact points is extremely important when drawing the FBD

I found it helpful to setup moment equations about the contact points with the ground for each of the disks in this problem.

when setting up the problem I found it helpful to take the moment about the no slip point

Remember for this problem to properly account for the radii difference between the disks when converting between coordinate systems.

I suggest drawing three independent FBD's for this problem as you can solve for the friction forces and relate all of them to get the EOM. When drawing the friction forces be careful, example 6.A.3 is helpful for this portion.

When solving for this problem it would be helpful to note you need to begin by creating three Free Body Diagrams. After listing all forces, the free bodies can be used to solve for the recurring forces in each equation (the only summation in X needed is the one for the bar). Once solving for the frictional forces on the bar, the equation of motion can be easily derived.

For the second part, you need to interpret the effect that halving the frequency will do by calculating how that affects the final answer.

Remember the angular accelerations are different for each disk.

Hope this helps best of luck.

Remember to break the system down to 3 separate FBD with equal and opposite forces of f_A and f_B for ease of analysis. Doing so will also properly account for the radius difference

Using the three FBD's to solve in terms of the friction forces is a method to solve this problem. Additionally, for part (b), example 6.C.4 is helpful.

It is important to account for the different sizes of both disks when calculating the moment about a point.

I recommend having 3 separate FBDs for each component and naming the normal forces with the opposite but equal interactions in mind.

After solving this problem similarly to previous homework, I wonder is using work energy equations would simplify the process. In particular relating KE to x dot and theta dot.

To make the problem easier to understand I drew three separate FBD to show the different parts

Calculating the moment around the non-slip points can simplify the equations, provided the parallel axis theorem is applied. Additionally, attention to signs and directions is crucial. Creating multiple free body diagrams can aid in generating equations

When setting up the free body diagrams for both disk A and disk B, remember to take into account that each system experiences multiple normal forces as well as multiple forces of friction. This information is needed to solve for part A and part B of the problem.

For this problem, you must find the moment at the center of gravity of A and B. This will help you derive the EOM.

I used the moment at the instant center's of the ground's contact with the wheel and found any answer.

For me solving this problem, the most important thing was to write out every Newton and Euler equation for each body before I began solving for the EOM.

For this problem, multiple moment of inertia equations can be used to simplify the force equation in the x direction. Remember to take into account the signs when setting up the different moment of inertia equations.

What is the best way to determine the direction of friction in these problems?

I would look at the direction the disks are moving. Then I would image how the disks are rotating to determine which way friction would have to act to prevent the disks from slipping.

As Kenneth stated, look at the direction of motion for the disks. Moreover, you can look in the previous homework hints as a placeholder for understanding of the direction.

In part B of the problem, only the coefficient of A needs to be solved for in order to determine the amplitude of the system because the system is undampened. Therefore, the coefficient of B is equal to 0.

I would recommend keeping your work in variables until the very end, this helped me keep my work organized. Additionally the "concluding remarks" at the end of each daily schedule are always helpful to reference for relevant equations!

To connect the 3 separate equations of motion, is the best way to do so to write kinematics equations for accelerations?

Would It be possible to solve this problem using the Conservation of momentum seems like it would be possible?

For this problem, I would strongly suggest drawing free body diagrams for all three parts of the system. Then using the force and moment equations of these free body diagrams, you can relate each of these into one system EOM.

6.A.3 is helpful when figuring out the way friction interacts with the system. Remember that the bar must maintain a no slip point with the balls.

Ad with very similar past HW problems, I found it very useful to take the moment around the contact point and then relate if with the given equation and sum of forces.

I referenced example 6.C.1 to help in my analysis, specifically its method of finding the derivations for the particular solution as the math was quite similar. Splitting the components of the derived particular solutions led me to isolate the cos and sin components which helped me to find the necessary amplitude value for part B.

I found it helpful to take the moment around the top of each disk. Using 3 free bodies is also helpful.

Start with taking the moment around the contact point. This helps remove and cancel out unhelpful variables.

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