# OCR Physics A G484 - The Newtonian World - 11th June 2015Watch

3 years ago
#1601
Did the resonance graph have to start at 0?
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3 years ago
#1602
Did you have to add the volumes up or use the volume of the first container? They were ****in vague. How do I know if the valve allows the gas to go back into the helium container or not? I assumed it doesnt so used the first volume.
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3 years ago
#1603
(Original post by maattwileman)
had to state newtons law of gravitation as a word equation hence you need to define G. another mark lost..
So would this be wrong i wrote: Force between two point masses is directly proportional to the product of their massess and inversely proportional to the square of the distance between them.
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3 years ago
#1604
(Original post by alanconnel)
So would this be wrong i wrote: Force between two point masses is directly proportional to the product of their massess and inversely proportional to the square of the distance between them.
Thats stating Newtons G law. It asked for the equation in words (F=GMm / r^2
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3 years ago
#1605
(Original post by Tazmain)
That's what I did, thought because it was a constant force, amplitude would be lower, but not decreasing...
Of course a constant force would make it so the amplitude is decreasing. A constant frictional force will slow the object down over time, hence decreasing its amplitude.
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3 years ago
#1606
(Original post by alanconnel)
So would this be wrong i wrote: Force between two point masses is directly proportional to the product of their massess and inversely proportional to the square of the distance between them.
well probably dw i put that also. why else would they clearly state word equation never have before
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3 years ago
#1607
(Original post by fatart123)
For the oscillating object that has its frequency slowly increased, does the amplitude remain the same and the only change as f increases it that the graph gets squashed together?
I graphed it as velocity over time, as f was increased velocity was increased and graph got squished together.. It said in the Question that the amplitude stayed constant I believe. Someone correct me if im wrong please.
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3 years ago
#1608
(Original post by alanconnel)
So would this be wrong i wrote: Force between two point masses is directly proportional to the product of their massess and inversely proportional to the square of the distance between them.
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3 years ago
#1609
(Original post by SkilledNChilled)
really???
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3 years ago
#1610
(Original post by aleishahogan)
Also where was like circular motion and Brownian motion o.o
There was circular motion knowledge needed in the question which asked us to derive Kepler's 3rd Law. I don't think Brownian motion came up explicitly, although not much can be said regarding it other than the standard "rapid, random, haphazard motion of particles"...
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3 years ago
#1611
(Original post by alanconnel)
So would this be wrong i wrote: Force between two point masses is directly proportional to the product of their massess and inversely proportional to the square of the distance between them.
Well it's not really a word equation but you never know with OCR. I wrote the same thing then put gravitational force of attraction between two point masses = gravitational constant x mass one x mass two / ( the separation between the masses)^2
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#1612
(Original post by verello12)
I graphed it as velocity over time, as f was increased velocity was increased and graph got squished together.. It said in the Question that the amplitude stayed constant I believe. Someone correct me if im wrong please.
I did a second graph like that

But we're wrong apparently

The constant amplitude refers to driving force of oscillator it seems
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3 years ago
#1613
(Original post by ETRC)
what the actual **** you had to define G?. I just wrote product of masses times G and said what G is. If you had to define G then the question is BS for 1 mark only.
This paper is the definition of ****.
I put that Newton's law of gravitation states that any two point masses attract each other with a force directly proportional to the product of their masses and inversely proportional to the square of their distance. I'm sure that'll be fine for one mark... right?
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3 years ago
#1614
For the word equation question, I wrote it as a word equation. Like it asked.
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3 years ago
#1615
(Original post by lexl23)
Got spit roasted by ocr AGAIN.
Ah man don't worry mate
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3 years ago
#1616
(Original post by SH0405)
For the word equation question, I wrote it as a word equation. Like it asked.
Same. Literally wrote: Force is equal to the product of the two mass by the Gravitational constant, over r squared
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3 years ago
#1617
(Original post by olil1996)
If I remember correctly, the small container had a pressure of 5x10^7 Pa, a volume of 2x10^-3 and a temperature of 20 degrees celcius.
pV=nRT so n=pV/RT
n=5x10^7 x 2x10^-3/8.31 x 294 = 41.1 mol
The larger container contained 45 moles of the gas and had a volume of 1.2x10^-2 so total number of moles is equal to 41.1 + 45 = 86.1 mol and total volume = 1.2x10^-2 + 2x10-3 = 0.014 m^3
p=nRT/V = 86.1 x 8.31 x 293 / 0.014 = 1.5x10^7 Pa
It told you how many moles were in the first container in the question itself I think, right?
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3 years ago
#1618
(Original post by maattwileman)
Did the resonance graph have to start at 0?
I'd have thought so yes, because at 0Hz, it won't be oscillating and won't have any amplitude.

However it may not be a marking point.
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3 years ago
#1619
you know the question to prove keplars 3rd law. was that the one when you had to derive that t squared = 4pi ect equation?
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3 years ago
#1620
(Original post by verello12)
It told you how many moles were in the first container in the question itself I think, right?
Why are people adding the volume? It said volume of tank.
0
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