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Magpie
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I got the same answer with my own equations. 
As you can see there was a lot of erasing.
[Edited on 17-8-2015 by Magpie]
The single most important condition for a successful synthesis is good mixing - Nicodem
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blogfast25
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Your equations are different? If so I'd like to see them.
[Edited on 17-8-2015 by blogfast25]
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Magpie
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I edited my post to include a photo of my calculations. If you can't read it I can provide a better edition.
[Edited on 17-8-2015 by Magpie]
The single most important condition for a successful synthesis is good mixing - Nicodem
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blogfast25
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They're the same, except you filled in the numerical values of the angles right from the start. No problem with that, of course. There really is only
one solution to this kind of problem.
And I honestly can't see the erasing...
[Edited on 17-8-2015 by blogfast25]
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gatosgr
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bad diagrams people stop confusing OP
[Edited on 17-8-2015 by gatosgr]
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Magpie
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You're right, of course. The only difference might be in the use of different trigonometric identities, eg:
Sinß instead of Cos (90°-ß)
gatosgr: I'll see if I can make a better diagram.
[Edited on 17-8-2015 by Magpie]
[Edited on 17-8-2015 by Magpie]
The single most important condition for a successful synthesis is good mixing - Nicodem
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MrHomeScientist
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gatosgr, didn't you say you were leaving the thread way back on page 2?
Very interesting physics problem, by the way. I always enjoyed drawing free body diagrams!
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blogfast25
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Promises, promises, MrHS... promises, promises.
Strange also how someone who considers free body statics problems 'not physics' (or not 'worthy' of physics or whatever Mr no need to
puncuate gatosgr actually meant) keeps coming back to this thread...
I think he should concentrate on preparing HCl his favourite way:
Quote: Originally posted by gatosgr  | Are drain cleaners allowed or should we bubble chlorine gas through water to make HCL [sic]? Electrolysis and such... although drain cleaners are very
common everywhere.
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[Edited on 17-8-2015 by blogfast25]
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Magpie
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Here's my sketch in "paint." I hate drawing with a computer - it's so slow and tedious. I might add the calculations later.
The single most important condition for a successful synthesis is good mixing - Nicodem
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blogfast25
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A lot faster than Etch A Sketch, though!
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blogfast25
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Here’s an interesting mechanics ‘free body’ problem but not a Statics one.
A mass m is dropped from a sufficiently high platform, while attached to a sufficiently strong elastic rope of unstretched length l
(the other end of the elastic rope is attached to the platform). The elastic rope behaves like a Hookean spring.
When the mass m is merely suspended from the platform by the elastic rope, the stretched (equilibrium) length of the rope is twice the
unstretched length.
Prove that when the mass is dropped from the platform while attached to the elastic rope it falls to a depth of:
d = (2 + √3) l
Ask for any clarifications, if you need them. Enjoy!
[Edited on 18-8-2015 by blogfast25]
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Oscilllator
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I get d = (3 + 2√2)l 
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blogfast25
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I haven't checked your solution completely but I can see one simple error: at equilibrium mg = kl, not 2kl. For a Hookean spring,
extending force = spring constant (k) times spring extension (NOT spring length). Here spring length at equilibrium is 2l, so spring
extension is 2l - l = l, not 2l.
Solving this as an energy conservation problem is of course the right way of doing it.
[Edited on 18-8-2015 by blogfast25]
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Oscilllator
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That's probably it. In my defence though, I had a lecture in 15 minutes at the time I started the problem.
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blogfast25
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Try that correction and it should work, I think. Haven't had time to verify it myself.
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fluorescence
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I found another one in this years exercises.
There is that sqared ladder frame that moves with a speed v = a*t
into a magnetic field that changes it's strengh over time.
So this is a combination of two known problems. The question is for
the induced Potential/ Current (U), don't know how to correctly call that in English. The even gave a formula for the magnetic field ( I marked that
orange).
So I went through some books and found the following lines (marked blue) since it's hard to find that much on that topic.
This is for a different shape that a simple linear conductor. So like the shape I have. It's said that the change of Φ with time can be made into a
sum of two Φ.
Φ1 equals the induced potential for the change of the magnetic field where Φ2 is for a movement of the frame.
Now I have my problems integrating that. Isn't the given formula (orange box) already the integral for the equation Φ1 ? Since I dunno how to
integrate that. What do I integrate that for ? I have a dependecy on t so shouldn't there be a dt somewhere ? Do I have to integrate it for dA since
this is the only thing that is mentioned in that equation.
And then there is this ring integral Φ2. I dunno how to solve these. I know there is a formula for a straight conductor U = BlV. But that has no
area in it. I'm not sure how to solve that one ? Can I use that given formula as solution for Φ1 already ?
Edit:
I thought about that Φ2 again.
U for a moving linear conductor in a magnetic field should be
U = n * ΔΦ/Δt where n is equal to 1.
And Φ is defined as Φ = B * A
No I just asume B to be constant for a second and just deal with A.
A is like the only thing that changes now where
ΔA = l*v*Δt
So U = n * ΔΦ/Δt = B * ΔA = B*l*v
So the area is not important for that step ? Do I have to add up all four sides of the frame to get the lenght ?
And then question is for the Φ1. Do I just take that formula and define B here as non constant and just use the information in the box. Or do I do it
as said in the blue box and calculate two Φ's and then add them up. But if so, how do I have to treat the B in Φ2, constant or not constant ?
[Edited on 18-8-2015 by fluorescence]
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fluorescence
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Okay so I tried to figure out another
solution. Perhaps this could be better.
At least I think I'm close to the solution now
although there are some unknown letters
left.
Could this perhaps be anything close to an
answer to the question ?
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fluorescence
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So today was my physics exam. It was quite hard, nearly nothing on mechanics,
thermodynamics or waves, most was on electromagnetism and there was only
one inclined plane which was quite cool and took me a moment to understand.
Now I don't want to hear a solution since I just hope mine was correct and I don't
want that to ruin my holidays now but just to keep you updated on how it acutally was.
There was an inclined plane with a mass (with a charge ) on it that slides down ( no rolling ). A
Magnetic Field is ponting into the background and the question was when so at
what time the obejct lifts off which was quite cool and most of the students I asked
didn't came up with the solution.
I just wanted to say thank you to all of you for the support !
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blogfast25
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All the best!
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