Things People Learn Wrong in School?


by Bboy Physics
Tags: learn, people, school, things
Bboy Physics
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#1
Jan3-13, 10:55 AM
P: 9
Hello PF!

What are some common things you see among peers in physics that they learned wrong in school? I'm talking about misconception(can you believe some college students think that the electrons are in a planetary orbit around the nucleus of an atom?!!?). I'd like to avoid looking like an idiot later.

I've seen minutephysics common misconceptions video if you're planning to link that to me.
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n10Newton
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#2
Jan3-13, 11:29 AM
P: 108
In my country,Science is being taught about wrong facts comparing to modern age but they are in historical order. As Chemistry/Modern Physics (Atomic Structures) is start with Dalton's Law dealing with Atom can't be divide but later (in upper classes) same teacher say Atoms can be divided in Electrons, Protons etc.
MrWarlock616
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#3
Jan3-13, 11:50 AM
P: 154
Quote Quote by n10Newton View Post
In my country,Science is being taught about wrong facts comparing to modern age but they are in historical order. As Chemistry/Modern Physics (Atomic Structures) is start with Dalton's Law dealing with Atom can't be divide but later (in upper classes) same teacher say Atoms can be divided in Electrons, Protons etc.
lol..

galleon
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#4
Jan3-13, 12:15 PM
P: 2

Things People Learn Wrong in School?


The idea that fundamental particles are spheres with some finite radius has to be one of the most prevalent.
Jasso
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#5
Jan3-13, 12:46 PM
P: 102
One of the biggest things that gets me is the concept of relativistic mass, i.e. that mass increases at relativistic speeds. It's led to more than a few misunderstandings on these forums, mostly from thinking that a fast enough particle will turn into a black hole because of it.
sjb-2812
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#6
Jan3-13, 12:52 PM
P: 418
Are these really "wrong" or more "lies to children", though? ( http://en.wikipedia.org/w/index.php?...ldid=529553882 )
johnqwertyful
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#7
Jan3-13, 01:39 PM
P: 308
In math, a lot of people have strange ideas about infinity or convergence. In my intro to real analysis class, the teacher asked if the set of all numbers 1/n where n is a natural number, has a minimum. Everyone obliged "yes, 0". Because 1/n "converges" to 0. People somehow think that converging means that it ACTUALLY "BECOMES" 0.
MrWarlock616
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#8
Jan3-13, 01:58 PM
P: 154
BODMAS and other similar rules (and how people, including me, thought that division and multiplication aren't of equal precedence), is creating a lot of discussion here and on Facebook.
Chestermiller
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#9
Jan3-13, 05:09 PM
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In my grandson's elementary school science class, they did a science experiment where they rolled a solid cylinder and a hollow cylinder made of the same material down an inclined plane. The solid cylinder got to the bottom faster. The students were asked the reason for this. Their explanation was that the solid cylinder weighed more, so it got to the bottom faster. The teacher happily accepted this explanation.

On the Bob the Builder TV show, there was a fictional thunder storm, and the characters were talking about how fast the sound travels from the point of the lightning strike to where you are located. The answer was that it travels one mile every second, so if you see the lightning and then 5 seconds later you hear the thunder, the lightning struck 5 miles away. I pity the poor schoolkid who really believes this, since the danger is much closer than he thinks.
Bboy Physics
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#10
Jan3-13, 05:16 PM
P: 9
I'd also like to add that I remember in elementary how my science teacher got a plastic cup with water in it, put a postage on top of it, flipped it, and let go of the postage and it wouldn't let go(because of atm). Her explanation? The water was sticky.
CWatters
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#11
Jan3-13, 06:01 PM
P: 2,861
On the Steve Wright show (BBC Radio 2) this past week they read out their usual list of "Factoids". If I heard correctly one was...

"The furthest you can send a DC electrical signal is 3km"

Well ok I know what they were trying to say but it's certainly lost a bit in the editing somewhere.
CWatters
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#12
Jan3-13, 06:03 PM
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When I was at school (<1978) two of the subjects I studied were Physics and Applied Maths. There was some overlap which sometimes caused problems.

In physics class the syllabus taught us that friction was independant of contact area. That makes sense - you might think that increasing the contact area would increase friction but it also spreads out the load over a larger area so net effect could reasonably be zero.

However the Applied Maths syllabus seemed to use a different definition of the coefficient of friction. That required us to factor in the contact area. We did raise this contradiction with our teachers but were just told we had to remember which exam we were sitting in and answer accordingly!

We must have done because we passed with good grades.
CWatters
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#13
Jan3-13, 06:15 PM
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There are a few misconception to do with electricity and magnetism....

Many people think electrons flow very fast (perhaps at the speed of light) and all the way around a circuit the instant it's switched on.

An equal number think magnets are an infinite source of energy and cite fridge magnets as proof.

Lots think that the Back EMF of a motor is the reason its not 100% efficient.
Jimmy
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#14
Jan3-13, 06:23 PM
P: 633
Quote Quote by CWatters View Post
There are a few misconception to do with electricity and magnetism....

Many people think electrons flow very fast (perhaps at the speed of light) and all the way around a circuit the instant it's switched on.
In my high school electricity/electronics class, we were taught this "fact".
davenn
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#15
Jan3-13, 09:55 PM
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Quote Quote by Jimmy View Post
In my high school electricity/electronics class, we were taught this "fact".
too many of us were ... me included.
Only thanks to spending a decent time on PF have I learnt the error of the teaching
there's may other things too that PF have cleared up. eg...

the Big Bang WASNT a point source explosion of matter

Dave
Damo ET
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#16
Jan4-13, 03:49 AM
P: 74
This thread may end up being quite informative for more than a few, if only the general public would read it!

To follow on with a similar theme, I had a near on stand up argument with a Tech professor whilst doing a math portion of a Trade qualification. He was teaching us about capacitors ect ect, and mentioning that the biggest capacitors were around 1000 micro Farads. I chimed in and said you could get 1/2, 1 and upto 2 Farad for automotive sound systems. He basically said I didn't know what I was talking about and must have the sizes wrong. Also in his class around the same time, we were discussing magnets. I mentioned that home theater speakers which are placed near the tv (usually center speakers) have screened/shielded magnets to prevent image distortion on the tv. He said "No, they wouldn't have a strong enough field to effect the image. The shield would be for some other reason."
Some people just don't want to know.


Damo
0xDEADBEEF
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#17
Jan4-13, 06:01 AM
P: 824
There is a tendency even among physicists and good teachers, to believe something is a fact because they have a cheap explanation for it. Sometimes the explanation is wrong and sometimes even the fact is wrong.

Stuff that comes to mind:
(wrong theory)
- The wire with weights cutting through a block of ice. It is often used as an example for a shift of the melting point under pressure. As far as I remember the correct explanation had something to do with thermal transport and molecular surface effects
- Bicycle pumps as an example of gas heating under compression when it is mostly friction otherwise the tires would get just as warm
- constant travel time around the airplane wing explains lift

(wrong facts)
- Resonance catastrophe stuff: Bridges collapsing due to soldiers marching has never been reported
- same for singers breaking wine glasses (at least it doesn't work for non defective glasses)
- the different areas of taste buds don't exist but children are encouraged to prove the teacher by testing it
- whole grain bread turning sweet while chewing due to enzymes turning starch into sugar (usually this type of bread is so sour that you won't taste any sweetness)

I am sure that there are many more...
johnbbahm
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#18
Jan4-13, 10:12 AM
P: 135
The only one that comes to mind is the answer to "What do we need Algebra for?"
The standard math teacher answer is not that good, and sounds like,
You have to have it to do higher level math,(very true, but not complete.)
The best answer I ever heard went like this.
"Numerical data comes in all forms, often that form is not useful.
Algebra is a methodology for converting data from an unusable form to a usable
form, and being assured of the results."


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