Question about this problem and Walter Lewin's video


by flyingpig
Tags: lewin, video, walter
flyingpig
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#1
Mar30-11, 05:03 PM
P: 2,568
1. The problem statement, all variables and given/known data





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The problem is EXACTLY the same.

But one thing concerns me. The answer key said the force is [tex]-27\mu N \hat{i}[/tex]

From Walter Lewin's method, I got [tex]+27\mu N \hat{i}[/tex]. Help?


3. The attempt at a solution
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flyingpig
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#2
Mar31-11, 11:47 AM
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Is no one answering because no one is bothered to watch the video lol?
flyingpig
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#3
Apr5-11, 07:05 PM
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Please...

Antiphon
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#4
Apr5-11, 08:03 PM
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Question about this problem and Walter Lewin's video


Flip the paper over. Then your i-hat will point the same way his does.
SammyS
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Apr5-11, 10:35 PM
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Quote Quote by Antiphon View Post
Flip the paper over. Then your i-hat will point the same way his does.
@Antiphon: Nice answer!

@fp: He means left to right, not top to bottom.

LOL
SammyS
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#6
Apr5-11, 10:48 PM
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Seriously, Mr. Lewin clearly states that the force is toward the left.

Therefore, it's in the [tex]-\hat{i}[/tex] direction.
flyingpig
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Apr6-11, 02:32 PM
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Quote Quote by Antiphon View Post
Flip the paper over. Then your i-hat will point the same way his does.
If you flip the paper over, how can you see your work?
SammyS
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Apr6-11, 05:21 PM
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Use thinner paper, write darker and/or use a light table.
flyingpig
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#9
Apr6-11, 05:36 PM
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...

but what if I want to do it mathematically?
SammyS
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Apr6-11, 07:37 PM
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Quote Quote by SammyS View Post
Seriously, Mr. Lewin clearly states that the force is toward the left.

Therefore, it's in the [tex]-\hat{i}[/tex] direction.
Did you see this?
Andrew Mason
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#11
Apr6-11, 11:24 PM
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Quote Quote by flyingpig View Post
The answer key said the force is [tex]-27\mu N \hat{i}[/tex]

From Walter Lewin's method, I got [tex]+27\mu N \hat{i}[/tex]. Help?
How do you get the force going to the right?

AM


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