What to do if your professor is not much ''intelligent''?

[micromass]

A 2 kg body is supported by a massless string. The body is accelerating downwards at a rate of 4.9 m/s^2. Calculate the tension on the string.

(It was pretty odd that this question is in the midterm exam and is worth 10 points.)

What I did was:
From F = ma:
T + (-mg) = -ma (Took the tension T as positive, therefore the weight -mg, is negative since the force is exerted on the opposite direction. The resultant force of this body is downwards, same direction with the weight, as stated in the question, -ma.)

T = mg - ma
T = 2 kg ( 9.8 m/s^2 - 4.9 m/s^2)
T = 9.8 N
T = 10 N


Her solution was a bit different because she chose the direction of the motion of the body as the positive direction. Either way, the answer should have been the same. Hence, the weight is positive, so is the direction of the resultant force, and the tension negative because it is on the upwards direction.

mg - T = ma
T = mg - ma
T = m (g - a) (This was where it went wrong, I think)
T = 2 kg [ 9.8 m/s^2 - (-4.9 m/s^2)] (The acceleration was negative because it was going "down", she explained)
T = 29.4 N (Again her answer was not in the correct significant figures.)


Most of my classmates had the same answer as mine.

Please forgive me if my solution is wrong.

Hahaha! Ask her: what if the body was accelerating downwards with a rate of more than g. Intuitively, it should put no tension on the string, and your answer indeed gives that. Put her answer would be that it put more tension on the string than without acceleration!

 

[Null_]

Wow, that's quite a mistake she's defending. Her argument makes no sense, and even if it did, she should have made "g" -9.8, thus giving her the correct magnitude of tension. I think you should consult with another professor or your academic adviser. If you have a TA, then go to him/her first. This isn't just an issue of a few marks on an exam (although that in its own right is a worthy cause), but it is also an issue of your classmates receiving the education you are paying for. There's no reason why someone with a BS in ChemE couldn't be a good physics professor, but yours obviously shouldn't be teaching.

 

[nlsherrill]

Oh, right. Thanks, Doc Al. :)

Thanks everyone. I'm still undecided whether or not I would bring this up with another professor. I'm afraid she would get pretty mad at us. One thing I've realized is that sometimes you have to decide whether the ''right thing'', (technically) is the right thing to do (politics of academia; must obey authority).

Regards to the professor background issue: I've never had a professor with a Ph. D. I've never heard of a professor with a research Ph.D that teaches in the university, I know of two professors who has Ph.D. in education. The university has a student population of 50,000 undergrads.

Dude...DO SOMETHING about this. I would be so infuriated by this. Your PAYING and spending your life on this and your teacher has no idea what they are talking about. I always call teachers out when they say something insane because I don't want all the other kids in the class thinking what ludicrous statement they just said was actually true. Thats just something I can't let get away, so maybe that's me. You said 7 out of 51 people failed the test? What if you get an F or D in this class? Will that prevent you from taking anything else? What if this happened, and it was all because you didn't stand up and do something about it when you knew you should?

Anyway, I looked at your work and that's exactly how I would have solved it, and its been confirmed by multiple physicists(I think?), so you have plenty of support.

 

[Ashuron]

Dude...DO SOMETHING about this. I would be so infuriated by this. Your PAYING and spending your life on this and your teacher has no idea what they are talking about. I always call teachers out when they say something insane because I don't want all the other kids in the class thinking what ludicrous statement they just said was actually true. Thats just something I can't let get away, so maybe that's me. You said 7 out of 51 people failed the test? What if you get an F or D in this class? Will that prevent you from taking anything else? What if this happened, and it was all because you didn't stand up and do something about it when you knew you should?

Anyway, I looked at your work and that's exactly how I would have solved it, and its been confirmed by multiple physicists(I think?), so you have plenty of support.

True
This is something you are usually encountered in high school level..not in university

 

[DR13]

After I argue with the professor, I went stupid and decided to not pretend to listen anymore, (I usually study at home with MIT CW, because most of the time I can't understand her) read a novel from my phone.

She caught me and asked me to go out and not attend her lectures anymore, and to just see her on the final exam. She's mad at me, that's for sure.

WHAT?? That is rediculous! How can she kick you out for being disinterested? In an intro class like yours most people are disinterested (sad, but true). Plus, you pay to take that class. I am not sure if she can legally do this.

 

[zketrouble]

@Doc_Al: It is impossible to argue with her, I doubt she has a clear understanding of the topic. Before (on the equilibrant, resultant issue), when I tried to argue from what I have read from my book about the definition of the term, she remarked that she doesn't care what I had read on my textbook.

So it sounds like you've stated your concerns to this teacher before. So now you can be pretty sure nothing will come from reasoning with her, so I would contact the dean of physics or dean of student services, or really any administrative body that can overrule any of her bad decisions.There's a good chance the dean will try to convince you nothing is wrong with her grading/teaching and that its simply her course policy, so it would be wise to find as many students as you can that have the same problem as you and see if they will call the dean about the same issue; then the dean doesn't have much a choice other than to review the issue and eventually solve it. 1/7 of the midterm exam is a big enough deal to make it worth pursuing corrections in my opinion. I assume that would diminsh your final grade by a few percent anyway, and it always sucks to fall one or two percent short of getting a higher letter-grade.

I understand that you are frustrated, and I can't say I blame you, but DONT SHOW YOUR ANGER WHEN DISCUSSING THESE ISSUES WITH THE DEAN. Getting angry will only make him think you are just another student that can't live with the fact that he has to take a physics course. Give the administrative officials the impression that you are a reasonable person and that you are concerned that there was an error on the midterm.

 

[G01]

You should talk to either the department chair or the dean. A pass/fail rate on a midterm of 13% screams "Problem!"

But your professor grudgingly not admitting that they were wrong in this comical case is even worse. Perhaps the professor is in over their head,teaching this course outside of their field, and is compensating by acting overly authoritarian. You should take some kind of action sooner rather than later. This is your education.

However, I am also concerned that you are at a university with 50,000 students and you have never seen a professor with a PhD? This doesn't seem right. Most universities won't let anyone without a Masters teach(grad students being the exception), and won't grant tenure(or sometimes even full time status) to someone without a PhD.

 

[Shackleford]

The gravitational force on the object is 19.6 N. If the force from the tension is 29.4 N, it should be going up. That's my cursory conclusion at this moment. lol.

 

[gb7nash]

She sounds like a tool and very immature. I'm surprised your school allows someone with a bachelors degree teach a college-level class. I would bring a group of students and complain to the dean to sort her out.

 

[qspeechc]

I'm surprised they let her teach! What I seriously suggest is that everyone in the class who wants to should come together, put down all your complaints, detail them in a document and present it to the Head of the Physics Department (or Dean, whatever the person is called). This should carry a lot of weight. I do not think this is something you should forget about, because it seems this person is not competent to teach the course, and you are suffering for this, not only your grades but your education too, and she may teach more courses yet!

 

[flyingpig]

Nothing ambiguous about the question.


Perfectly correct.

This is going soo off topic, but is it bad that I also got the same answer as her prof?

The body is going down with (in) the direction of gravity, so it should be 2kg(9.8m/s² + 4.9m/s²) = 29.4N?

 

[Doc Al]

This is going soo off topic, but is it bad that I also got the same answer as her prof?

The body is going down with (in) the direction of gravity, so it should be 2kg(9.8m/s² + 4.9m/s²) = 29.4N?

Well, it's wrong. (How did you arrive at your equation? Don't just guess.)

 

[flyingpig]

Well, it's wrong. (How did you arrive at your equation? Don't just guess.)

Both are going downwards, add the accelerations and multiply by 2kg

 

[Doc Al]

Both are going downwards, add the accelerations and multiply by 2kg

I can see that's what you did, but why? Where's the physics? What laws did you apply?

 

[flyingpig]

I can see that's what you did, but why? Where's the physics? What laws did you apply?

The formal way goes like this

mg - T = ma Since mg is "stronger" because it is "pulling"

mg - ma = T

m(g - a) = T

2kg(9.8 - 4.9) = T

2kg(4.9) = 9.8N

FBD that screwed me up was

[PLAIN]http://img638.imageshack.us/img638/9783/91018966.png

T = "mg + ma"

What the professor overlooked was that the problem said "accelerating downwardsat a rate of 4.9 m/s²"

The downwards part already specified the direction, adding any more signs would defeat the purpose, if it was worded like "accelerating at a rate of -4.9m/s², then it would be right no? Because I think that's what she read

 

[Doc Al]

FBD that screwed me up was

...

T = "mg + ma"

"ma" should not appear on a FBD.

What the professor overlooked was that the problem said "accelerating downwardsat a rate of 4.9 m/s²"

She didn't overlook it, she messed it up. Being charitable, she forgot that she took down as positive when she went to plug in the acceleration.

 

[flyingpig]

I might have been thinkinb about those elevator problems

 

[Ryker]

I might have been thinkinb about those elevator problems

Well, this is exactly analogous to the elevator problems, but she still made a mistake.

 

[Borek]

However, I am also concerned that you are at a university with 50,000 students and you have never seen a professor with a PhD? This doesn't seem right. Most universities won't let anyone without a Masters teach(grad students being the exception), and won't grant tenure(or sometimes even full time status) to someone without a PhD.

It may depend on the country.

 

[bobthenormal]

I agree 100% with zketrouble. Proceed very carefully! And if possible, try to act as a group instead of individually!

I agree also.

Even if you get the professor to admit fault, he/she may hate you and grade you with bias from then on.

It's not okay, and in a perfect system people who cannot admit their faults (or make too many mistakes) should be brought to justice, but this is not a perfect world. This is one area where learning that the system IS broken will help you.

The problem is also more complicated than you see it. Professors have egos (essentially a requirement for surviving graduate school) and end up develop a strong ability to intimidate their way out of these types of situations. It does not help that they often genuinely believe they are right because students routinely and boldly challenge them when they are NOT wrong. You probably have seen a student try to challenge the professor and be wrong, I see it regularly. That repeated behavior leads to a thick skin on these issues, and it's hard for the professor to backtrack once they've already asserted that they're right. It becomes more difficult for them to see the truth through their own bias.

I had this happen to me repeatedly on different scales ranging from publicly (in front of class) exposing the problem, to privately (in office hours). I have had the range of responses, some teachers are very comfortable with the fact that they make mistakes, others are mortified of the idea and will fight you to the death over it. And they have a lot more power than you do. In general, the only "safe" way to address the problem is to avoid being seen as an outlier. You have to address it with a group or not at all.

I once had this type of problem with a professor who ran a large research facility on campus and had an entire wing of the school named after him. So you also shouldn't expect that the higher you go, the better you get (i.e. the problem isn't just that your professor doesn't have an advanced degree). In the case of the professor above, it helped me realize that in research, money and results are the deciders. Mostly money. The more money you bring in the "better" you are, and it pays to be an intimidating and confident person when it comes to research grants.

--Bob

 

[Headacheguy]

Thanks for the response everyone. I'll try to convince my classmates about it.

I also would like to apologize for bringing up multiple issues on this thread that is not in the OP. I tend to do it every time. :uhh:

 

[flyingpig]

"ma" should not appear on a FBD.

I have this feeling you would say that

She didn't overlook it, she messed it up. Being charitable, she forgot that she took down as positive when she went to plug in the acceleration.

I looked at an elevator problem myself and for some reason I would tackle it completely differently and then I realize what this professor was thinking.

The "accelerating downwards" part meant that this is the NET acceleration.

 

[bobthenormal]

Not to pester, but just to help a bit (I used to tutor English to ESL students), the topic of your post uses "much" incorrectly.

Just recalling it off hand (there may be special cases I am not thinking of), it should be attached to a noun not an adjective, as in "much money," "much food," "much intelligence." A more natural sounding choice for English speakers would have been "very," i.e. "What to do if your professor is not very intelligent." or "What to do if your professor does not have much intelligence." (The 2nd one here sounds a little weird though.)

(Also, I'd note that the sentence sounds very insulting, I'm sure most people assumed you didn't mean it in such a harsh way or they would have said something about that... even though it seems well deserved in this case, haha.)

--Bob

 

[Headacheguy]

Hi Bob, thanks! English is not my first language, it's like a second language but still I can't express my thoughts that well.

Yes, I think the title is pretty harsh. I'll remember that... also the ''much'' + noun NOT adj.

 

[zketrouble]

Hi Bob, thanks! English is not my first language, but it's like a second language and still I can't express my thoughts that well.

Yes, I think the title is pretty harsh. I'll remember that... also the ''much'' + noun NOT adj.

Sorry for going off-topic, but out of curiosity, where are you from and what was your first language? Your English is pretty good, its at the same level as my second language (Chinese) and I've been studying for 12 years.

 

[mathwonk]

you should not give up. this sort of behavior is not typical of any professors I have ever known at least in math departments. there are exceptions, especially among some few unqualified persons on temporary hire, but an appeal to the chairperson should resolve it. you should not ever give into stupidity and unfair behavior, once you believe you are right.

I have not read your problem, and offer no opinion on it, but you can always make an appeal in a diplomatic way, and you should. You also seem to have enough support here for believing you are correct.

i am surprised that so many people here seem to think that complaining is a common reason to suffer more unfair treatment. where do you guys go to school, in a taliban stronghold?

 

[mathwonk]

the answer to your literal question however is to avoid unintelligent professors entirely.

 

[Headacheguy]

Thank you Mr. mathwonk, sir.

Until now I still haven't resolved it. My classmates don't want to do anything about it, pretty ironic since almost all of them failed the exam. So the only choice I have is to complain to her--again--myself. Letting it slip is out of the question. I tried to talk to other professors and found one who said he'll talk to her about it.

the answer to your literal question however is to avoid unintelligent professors entirely.

Our system is like high school. The department chooses our professors and we can't do anything about it.

 

[Metaleer]

It may depend on the country.

Indeed, in Spain (before 2007) one could become a permanent, civil servant professor with only the Licenciatura, which is roughly equivalent to a Master's degree.

Thank you Mr. mathwonk, sir.

Until now I still haven't resolved it. My classmates don't want to do anything about it, pretty ironic since almost all of them failed the exam. So the only choice I have is to complain to her--again--myself. Letting it slip is out of the question. I tried to talk to other professors and found one who said he'll talk to her about it.

Our system is like high school. The department chooses our professors and we can't do anything about it.

As someone pointed out, there's no reason a chemical engineering graduate can't teach physics - I've had a Ph.D in engineering teaching a mathematics subject, and he seemed to know the subject like the back of his hand. But this particular teacher should go back to school before she tries to teach more Physics!

It's a shame you can't decide who your lecturer is, as this would have most likely fixed the problem. As many people here have mentioned, the most important issue is to talk to someone else in a diplomatic fashion, so as not to appear like a student merely frustrated due to the fact that he has to take a Physics subject.

i am surprised that so many people here seem to think that complaining is a common reason to suffer more unfair treatment. where do you guys go to school, in a taliban stronghold?

Unfortunately, some countries/states/universities grant too much power to professors, and we all know what happens - power gets to your head.

In a Mechanics lecture, the professor forgot a minus sign and I nonchalantly pointed this out to him ("Excuse me, professor, shouldn't there be a minus sign there?"). And he flew off the handle ("OK, fine, I'll put a minus sign there if it pleases you."). About 15 mins later, when I raised my hand to ask him something, he flipped out ("What the f*** do you want now?!"). After that incident, I just decided to lay low.

 

[PhDorBust]

Anyone else not surprised that the professor is a 'she'?

 

[micromass]

Anyone else not surprised that the professor is a 'she'?

What has that have to do with anything? I've seen enough male profs which were not very intelligent to. And judging from your reaction, you don't seem very intelligent to...

 

[Astronuc]

Anyone else not surprised that the professor is a 'she'?

Gender is irrelevant.

 

[Shackleford]

He's basing his observation on some perceived, personal stereotype of his. Whether or not it's a common stereotype is up for debate. However, by disparaging his intelligence you've shown your own stereotype. It does not mean he's not intelligent "to."

 

[hikaru1221]

Until now I still haven't resolved it. My classmates don't want to do anything about it, pretty ironic since almost all of them failed the exam. So the only choice I have is to complain to her--again--myself. Letting it slip is out of the question. I tried to talk to other professors and found one who said he'll talk to her about it.

Hi,

If it's just "talk", then I doubt it will make the situation any better. Until you are sure that you can *sweep* her out, don't do anything "stupid". I mean it. Education is one thing; guaranteeing that you would *survive* to continue enjoying your education is another thing.

I'm pretty surprised that only 1 professor agreed to "talk" (just "talk"?!) to her. It seems that your physics prof is not the only one you have to watch out. Warning: you may encounter any of the professors that you talked to about this problem later on.

 

[Borek]

Anyone else not surprised that the professor is a 'she'?

In my personal experience there is no correlation between gender and level of competence.