Physics is just too hard.

  • Thread starter JJRKnights
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  • #1
JJRKnights
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I still can't even start a problem after hours of studying the subject. I feel like an idiot, or that I'm just trying to do something that I can't do.

The book that we use, nothing helps in it to solve the problems. All they give is the basic form of the equations. Doesn't tell you anything on how to use them, and when I see explanations for the problems I get even more lost than helped.

Has anyone ever felt in this position, I feel like no matter how hard I try I don't think I will ever even be average in physics. I have an F in the class for sure right now. Have 2 more tests to try and bring it up. But it seems like I'm falling in a black hole and can't do anything about it.
 

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  • #2
dacruick
1,042
1
Some people can't handle physics, I just know that from personal experience. I think that there has to be a very specific type of person, with specific problem solving abilities to excel in physics. Of course, I believe that anybody can do well in physics, as I believe anybody can accomplish something if they want to. But you might not want it enough.

my ex girlfriend got a 49 in university physics, she talked to the prof and bumped it up to a 51 (she was cute haha). I tried helping her many times but she was, like you, not comfortable with the questions. There was always this look of impending doom on her face when she was doing physics problems, and she did a heck of a lot of questions.

It is also very possible that the book you are using is not very well suited for you. Which textbook is it?
 
  • #3
JJRKnights
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Serway and Jewett 8th ed.

Also my professor is like russian, or indian or something and I can't understand him, which doubles my problem. I do want a good grade badly, It's just a gap in my mind on how to do physics. I do problems as much as I can, and never understand why the answers come the way they do.

I am an extremely rational person, yet it doesn't make sense to me how to solve these problems.
 
  • #4
bp_psy
468
8
If you haven't solved any problems during the "hours of studying" it means that you were not really studying physics.If it's an intro course you should read the theory quickly , take some notes and then start doing problems. If you spend more than half an hour on a problem then try another and return later on the hard one.Most lost time is due to getting some idea in your head and trying to do the same stupid thing over and over again. Taking a break from a problem may help you forget the stupid idea or realize that it is stupid.
 
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  • #5
hellboy4444
23
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The driving force to learn cannot be greed for good grades. So please rethink: "are you really rational?"
Forget about the professor. Get hold of ONE good textbook. Read it and do not proceed forward unless you convince yourself of the lines. Consult friends/teachers/physicsforums etc. Please forget about grades for a while, if you want grades to come to you instead.
Remember that I am writing all this because I think it is possible to overcome such difficulty.
 
  • #6
hellboy4444
23
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Are you trooling. That is one of the stupidest post in the "General Physics " forum.

"Trooling?" I don't get it. I stated a fact which I have observed around me.
 
  • #7
JJRKnights
53
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I do over 10 problems a day, usually taking me 30-45 minutes each, sometimes 20 mins or so. But I can't do problems within 1.5-3 minutes like I'm required to in the class. Some things already make sense to me, and I can work them out, but every time I see a new situation in a problem, I can't instantly recognize it and do it out within 1.5-3 minutes. So doing problems isn't really the problem, I do so many of them.

Idk, I just feel an extreme hatred towards the class right now. I would love to learn physics, it's just my brain seems to not be able to handle it.
 
  • #8
Low-Q
Gold Member
284
9
I still can't even start a problem after hours of studying the subject. I feel like an idiot, or that I'm just trying to do something that I can't do.

The book that we use, nothing helps in it to solve the problems. All they give is the basic form of the equations. Doesn't tell you anything on how to use them, and when I see explanations for the problems I get even more lost than helped.

Has anyone ever felt in this position, I feel like no matter how hard I try I don't think I will ever even be average in physics. I have an F in the class for sure right now. Have 2 more tests to try and bring it up. But it seems like I'm falling in a black hole and can't do anything about it.
Sounds familiar. Every time I find an equation for something I have been looking for for a long time, there is allways one factor or figure in the equation with no explanation that tells what it is. So there I am, still lost :biggrin:
 
  • #9
hellboy4444
23
0
Can I have a look at a typical question you handle at this level?
 
  • #10
pergradus
138
1
Serway and Jewett 8th ed.

Also my professor is like russian, or indian or something and I can't understand him, which doubles my problem. I do want a good grade badly, It's just a gap in my mind on how to do physics. I do problems as much as I can, and never understand why the answers come the way they do.

I am an extremely rational person, yet it doesn't make sense to me how to solve these problems.

If you can't distinguish between someone who's Russian or someone who's Indian then you probably aren't cut out to do physics...
 
  • #11
dacruick
1,042
1
If you can't distinguish between someone who's Russian or someone who's Indian then you probably aren't cut out to do physics...

LOL...this is true.

Either that or you don't go to class very much.
 
  • #12
JJRKnights
53
0
Rigid rods of negligible mass lying along the y-axis connect three particles. The system rotates about the x-axis with an angular speed of 3.70 rad/s.

http://img840.imageshack.us/img840/6571/10p026.gif [Broken]

(a) Find the moment of inertia about the x axis.

(b) Find the total rotational kinetic energy evaluated from 1/2[Iω^2].

(c) Find the tangential speed of each particle.
4.00 kg particle m/s
2.00 kg particle m/s
3.00 kg particle m/s

(d) Find the total kinetic energy evaluated from the sum of 1/2[mivi^2]

(e) Compare the answers for kinetic energy in parts (b) and (d).

Professor's first name is Russian based, and his last name is Indian, like from India. He's very skinny and has a tannish skin tone, white hair. It's hard to tell.
 
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  • #13
dacruick
1,042
1
Rigid rods of negligible mass lying along the y-axis connect three particles. The system rotates about the x-axis with an angular speed of 3.70 rad/s.

http://img840.imageshack.us/img840/6571/10p026.gif [Broken]

(a) Find the moment of inertia about the x axis.

(b) Find the total rotational kinetic energy evaluated from 1/2[Iω^2].

(c) Find the tangential speed of each particle.
4.00 kg particle m/s
2.00 kg particle m/s
3.00 kg particle m/s

(d) Find the total kinetic energy evaluated from the sum of 1/2[mivi^2]

(e) Compare the answers for kinetic energy in parts (b) and (d).

Professor's first name is Russian based, and his last name is Indian, like from India. He's very skinny and has a tannish skin tone, white hair. It's hard to tell.

Do you typically feel overwhelmed by this type of question? Or is this something that you can handle on a consistent basis?
 
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  • #14
pergradus
138
1
That's a very simple problem. You need to look at some other textbooks if the one you're using isn't clear enough for you to understand how to do that problem. Do you actually read your book, and following along with the example problems, or do you just skim looking for equations to plug into?

How far along are you into your calculus classes? If you aren't doing well in calculus you'll never do well in physics.
 
  • #15
hellboy4444
23
0
See, just remember that mostly physics theory is to do with somethings called 'laws'. Now what is a 'law'?
It is a proven truth! Some person saw something happening around him, thought it might be like 'this', so gave an equation with the help of his maths friend to find out quantities of interest.
I will proceed further once you are comfortable with the above.
 
  • #16
JJRKnights
53
0
I can do it if you give me like an hour lol.

The things I think that might be relevant to this problem are:

Iα = T
K = 1/2Iw^2

My instinct tells me
I = T/α would be the solution for a, but there is no T that I see.

Then here is where I go looking for help lol.

The only things the chapter shows for that problem are:

I = Ʃ(mi)ri^2
K_R = (1/2)Iw^2
 
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  • #17
hellboy4444
23
0
I can do it if you give me like an hour lol.

The things I think that might be relevant to this problem are:

Iα = T
K = 1/2Iw^2

My instinct tells me
I = T/α would be the solution for a, but there is no T that I see.

Then here is where I go looking for help lol.

I'm in Calc 3 right now, with an A. Calculus is much much easier than physics.

The only things the chapter shows for that problem are:

I = Ʃ(mi)ri^2
K_R = (1/2)I^2

There is a fundamental fault in your approach my friend. Brush up with the laws and definitions of terms. If possible, write them is a piece of paper and use this paper while you solve initially. Later on you won't need even these.
Use the laws and definitions only while you solve the questions. It is very straight forward and simple. Keep your mind open and use the laws and definitions to calculate quantity values. Do not attempt to match the answers at the back of your book. keep up with your self-dignity. Take help but also check if you can solve without taking help a few problems on your own totally. Take help to learn rather than to solve assignments. Ask general questions when taking help.
Like: Instead of asking someone to solve this problem, ask him/her:
"given a system of connected masses, how to calculate the moment/energy etc."
 
  • #18
Dembadon
Gold Member
654
89
"Trooling?" I don't get it. I stated a fact which I have observed around me.

I was going to let this go, but I want to correct your reasoning. You did not simply state a fact, you made an inference.

You are probably a girl, since I have found girls mostly not being driven by reason. Instead they go for emotional attractions. Try to be rational in life; you will definitely love Physics then.

emphasis mine

This is not a fact that you've observed, since you have not seen the OP in-person.
 
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  • #19
dacruick
1,042
1
I can do it if you give me like an hour lol.

The things I think that might be relevant to this problem are:

Iα = T
K = 1/2Iw^2

My instinct tells me
I = T/α would be the solution for a, but there is no T that I see.

Then here is where I go looking for help lol.

I'm in Calc 3 right now, with an A. Calculus is much much easier than physics.

The only things the chapter shows for that problem are:

I = Ʃ(mi)ri^2
K_R = (1/2)Iw^2

That would take you an hour on a test? Yikes!

Parallel axis theorem will help you for the moment of inertia. Once you have I(they give you w) you can find rotational kinetic energy. from w and r, you know the tangential speed of each of them. using that tangential speed you can find the kinetic energy using 1/2 mv^2. And then you just have to compare your two energy values.

Can you tell me where your hour would be allocated throughout this question?
 
  • #20
JJRKnights
53
0
There is a fundamental fault in your approach my friend. Brush up with the laws and definitions of terms. If possible, write them is a piece of paper and use this paper while you solve initially. Later on you won't need even these.
Use the laws and definitions only while you solve the questions. It is very straight forward and simple. Keep your mind open and use the laws and definitions to calculate quantity values. Do not attempt to match the answers at the back of your book. keep up with your self-dignity. Take help but also check if you can solve without taking help a few problems on your own totally. Take help to learn rather than to solve assignments. Ask general questions when taking help.
Like: Instead of asking someone to solve this problem, ask him/her:
"given a system of connected masses, how to calculate the moment/energy etc."

That's pretty helpful, is there any website on the internet where I can get all of the laws and definitions. My book doesn't do a good job with them.
 
  • #21
JJRKnights
53
0
That would take you an hour on a test? Yikes!

Parallel axis theorem will help you for the moment of inertia. Once you have I, you know w, so you can find rotational kinetic energy. from w and r, you know the tangential speed of each of them. using that tangential speed you can find the kinetic energy using 1/2 mv^2. And then you just have to compare your two energy values.

Can you tell me where your hour would be allocated throughout this question?

The hour in that problem:
30 minutes finding what to use, and failing at attempts to do them
10-15 minutes looking for a solution on the internet.
15-20 minutes doing the problem the way that it is supposed to be done.
 
  • #22
dacruick
1,042
1
The hour in that problem:
30 minutes finding what to use, and failing at attempts to do them
10-15 minutes looking for a solution on the internet.
15-20 minutes doing the problem the way that it is supposed to be done.

Why should you have to find what to use if its the test? Studying should cover that first 30 minutes worth of blunder, hopefully they don't give you the internet during exams, and 15-20 minutes doing the problem is very reasonable for a test.

Since this is a problem that you have seen before, why in the world should you fail numerous times at solving the problem? Are you just having trouble retaining solving methods?
 
  • #23
JJRKnights
53
0
Why should you have to find what to use if its the test? Studying should cover that first 30 minutes worth of blunder, hopefully they don't give you the internet during exams, and 15-20 minutes doing the problem is very reasonable for a test.

Since this is a problem that you have seen before, why in the world should you fail numerous times at solving the problem? Are you just having trouble retaining solving methods?

Problem like that would take me like an hour on my own time, on a test I would try, fail, and guess.. experience from 20 problems on my first test in the class.
 
  • #24
dacruick
1,042
1
Problem like that would take me like an hour on my own time, on a test I would try, fail, and guess.. experience from 20 problems on my first test in the class.

Why are you failing on the first try? And why do you come to this forum with the attitude that you've already failed? If you don't think you can do better then you wont. You should just create a thread titled "pity me because physics is hard". I'm sorry if I'm being harsh but you don't seem to want to be better.
 
  • #25
JJRKnights
53
0
Why are you failing on the first try? And why do you come to this forum with the attitude that you've already failed? If you don't think you can do better then you wont. You should just create a thread titled "pity me because physics is hard". I'm sorry if I'm being harsh but you don't seem to want to be better.

Well technically I already failed, I can't get better than a D now, even if I get 2 100's on the next tests. I just can't read a problem and know what to do, I know the basic things like K = 1/2mv^2 but then the prof comes up with some weird derivations. or like how you are supposed to know how to change it with each situation. I want to try to get the highest grade possible, it's just hard for me to comprehend how to get those other equations. Trust me, I've put atleast 100 hours into this class already, and I can't retain any information that I need.

Also, I have an issue with learning new things quickly, every time I get some concept we move on to another chapter, and we're already a couple ahead of what I learned. Right now we are doing angular momentum and stuff, chapter 11 for us, and I'm just now starting to grasp chapter 7 material
 
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  • #26
Harrisonized
209
0
If you're going to get a D for sure, drop the class. A W is infinitely better than a D. If you've spent 100 hours on the class and you still have a D, you're obviously not studying physics effectively. You may as well have spent that 100 hours playing a sport, because almost anyone can memorize the limited number of equations used in mechanics in 100 hours without learning the logic behind them. A true student, however, will learn the logic.
 
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  • #27
JJRKnights
53
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I can't afford to drop it. Financial aid pays for my classes if I drop I'll end up owing a couple hundred dollars.
 
  • #28
Harrisonized
209
0
That sucks. I'd rather owe a few hundred bucks than permanently have a failing grade on my record though. The former is is fixable; the latter is not. Maybe you should choose your classes more wisely next term.
 
  • #29
JJRKnights
53
0
Well, pursuing an engineering degree is the only reason I went to college. I will not quit, I deserve every grade I get and if I flunk out of college then I'll accept it, but I am following the plan the school has for mech engineering, and if I can't keep up I don't deserve to have the degree.
 
  • #30
1MileCrash
1,339
41
Wow, a lot of superiority complex going on in this thread..
 
  • #31
JJRKnights
53
0
Lol, seems that way. I want to be successful, things always hold me back. I've had depression for the past 4 years that comes and goes, but once I realized that physics was just too high level of a class for me, I became depressed again. It's one of the major areas that is required to be an engineer, and that's what I've wanted to be since I was younger. I for the life of me can't understand it. I came here for direct help because I am fed up with failing, can anyone help me out, like give me an example problem, and i'll show methods to the way that I would try to solve it? I just need some kind of interactive help, I'm an interactive learner, and lecture classes with hundreds of kids and 1 professor is pretty bad.
 
  • #32
dacruick
1,042
1
Lol, seems that way. I want to be successful, things always hold me back. I've had depression for the past 4 years that comes and goes, but once I realized that physics was just too high level of a class for me, I became depressed again. It's one of the major areas that is required to be an engineer, and that's what I've wanted to be since I was younger. I for the life of me can't understand it. I came here for direct help because I am fed up with failing, can anyone help me out, like give me an example problem, and i'll show methods to the way that I would try to solve it? I just need some kind of interactive help, I'm an interactive learner, and lecture classes with hundreds of kids and 1 professor is pretty bad.

Feel free to post any homework questions that you have problems with. People on this forum are more than happy to help, and they won't straight up give you the answer, they will make sure you find your own way through it. A method that I'm sure will help you is that after you've completed a question with assistance in any form, make note of it, and try it again tomorrow. If the steps don't come naturally to you, use your assistance again, and then make sure you try it again the next day.
 
  • #33
Dembadon
Gold Member
654
89
Good that you didn't drop it.

Actually yes, it is clearly an inference. Fact was about the second part of the statement, which is an observation.
This is merely a case of extrapolation. My assumptions, explicitly stating, were that the behavior of the subject is coherent with the behavior of other beings that constituted my surrounding when I made this observation. This is, however, needless to mention and therefore I didn't.
Very correctly said, correlation does not imply causation.
Remember that this was a guess as I said 'probably'. I, however, didn't impose this to be a truth!

I wasn't as clear as I should've been. I took issue with your use of the word fact, since I can't find a single one in your post.

... since I have found girls mostly not being driven by reason. ...
...Instead they go for emotional attractions. ...

Facts are verifiable by repeatable scientific experiment(s). I assume you haven't run scientific experiments on all of the women with whom you've come into contact. Even if you did, the sample size would be so small as to be meaningless and unhelpful to your position.

Additionally, the scientifically minded person realizes that casual observation often contains various forms of bias and imprecision.
 
  • #34
1MileCrash
1,339
41
Lol, seems that way. I want to be successful, things always hold me back. I've had depression for the past 4 years that comes and goes, but once I realized that physics was just too high level of a class for me, I became depressed again. It's one of the major areas that is required to be an engineer, and that's what I've wanted to be since I was younger. I for the life of me can't understand it. I came here for direct help because I am fed up with failing, can anyone help me out, like give me an example problem, and i'll show methods to the way that I would try to solve it? I just need some kind of interactive help, I'm an interactive learner, and lecture classes with hundreds of kids and 1 professor is pretty bad.

If you are good in math, you can do it. My recommendation is simple. Look at the physics formulas, and don't just memorize them. Understand WHY they work and you'll know when they can be applied, AND you'll never forget them. EVERYONE has to get help from time to time.

A simple example is my friend who kept forgetting the formulas for uniform circular motion. I said to him "look, when you take a sharper curve in a car, you feel more pull, right? So your formula has to reflect that, and that's why radius of the circle goes in the denominator. Likewise, more pull for more speed, velocity has to be at the top. (and square velocity, but you get the point)
 
  • #35
Jack21222
204
1
All they give is the basic form of the equations. Doesn't tell you anything on how to use them,

This is the part that confuses me. The students that come to me for tutoring say the same thing you just did, and I never know how to respond.

What do you mean by you don't know how to "use" an equation? You plug in all of your knowns, and solve for your unknowns. Or, you can solve for what you want to know in terms of what you do, and then plug in. Either way.

Sometimes, you'll have two unknowns, but two equations you can relate the quantities with.

Equations don't need an instruction manual; every equation is used in exactly same way.

Can you clarify exactly what you mean when you say you don't know how to use an equation? By "how," do you mean "when?" If so, you use an equation when it relates something you don't know to things you do know. First, try to find an equation that has only one thing you don't know and you know everything else. If there isn't one, try to find a pair of equations that relate your unknown to things you do know. Exploit conservation laws if possible to splice equations together.

That's really all it takes to get first the first 3 general physics classes.
 

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