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OCR Physics A G484 Jan 2012 - The Newtonian World

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Original post by Barkziee
Hey guys, the weekend before the storm is approaching, goodluck in your revision and the eventual exam!

Im focusing mostly on the "Thermal Physics" and "Ideal Gases" chapter. I don't study chemistry so I find some of the molar qualatative questions more difficult, whereas the circular motion and gravitational chapters come more natrually to me. One thing that confuses me somewhat is not mixing up the assumptions made as a result of Brownian Motion and the Kinectic Model of Gases.


I'm terrified. I don't know if I should be but time will tell!

I need to revise assumptions of Kinetic Model... I can only ever remember two and that's not good.
Reply 81
Avatar for Ralphus J
Ralphus J
Original post by Barkziee
Hey guys, the weekend before the storm is approaching, goodluck in your revision and the eventual exam!

Im focusing mostly on the "Thermal Physics" and "Ideal Gases" chapter. I don't study chemistry so I find some of the molar qualatative questions more difficult, whereas the circular motion and gravitational chapters come more natrually to me. One thing that confuses me somewhat is not mixing up the assumptions made as a result of Brownian Motion and the Kinectic Model of Gases.


I am exactly the same, hate Avagadro and this mole business so much, Can you please state the assumptions?
(edited 12 years ago)
Reply 82
Avatar for aquark
aquark
Original post by Ralphus J
I am exactly the same, hate Avagadro and this mole business so much, Can you please state the assumptions?


Gas consists of large number of rapidly and randomly moving particles
Negligible volume of gas particles
Negligible gravitational forces
No other intermolecular forces
Perfectly elastic collisions
Original post by aquark
Gas consists of large number of rapidly and randomly moving particles
Negligible volume of gas particles
Negligible gravitational forces
No other intermolecular forces
Perfectly elastic collisions


I always forget the elastic collisions! Trying to make a picture of all these so I can remember them :tongue:
Reply 84
Avatar for Ralphus J
Ralphus J
Original post by aquark
Gas consists of large number of rapidly and randomly moving particles
Negligible volume of gas particles
Negligible gravitational forces
No other intermolecular forces
Perfectly elastic collisions


Thanks and brownian?
Reply 85
Avatar for ChrisA7x
ChrisA7x
Sitting this exam but have neglected it recently for Maths D1 which was today and Maths C3 which is monday! I'm good at the maths type questions but tend to forget the wordy ones, like describe the experiment to find the specific heat capacity of a liquid. Ugh!
Reply 86
Avatar for Toshiya
Toshiya
1
Original post by ChrisA7x
Sitting this exam but have neglected it recently for Maths D1 which was today and Maths C3 which is monday! I'm good at the maths type questions but tend to forget the wordy ones, like describe the experiment to find the specific heat capacity of a liquid. Ugh!


I know the feeling, I had M1 today, have C3 Monday and have chem on Thursday and M2 Friday as well as physics Tuesday. Gonna try and get a fair bit of revision in this weekend.

I really wish there were more past papers around. Does anyone have points to include if they ask 'describe an experiment to show Brownian motion'? I know what the experiment is but I have no idea what to put.
Reply 87
Avatar for maddy93x
maddy93x
Original post by teachercol
Except that with only 14 marks between A and E last year. Thats about 3 marks per grade.

a 3 mark slip-up can be a awhole grade.

The A grade is low 44/60 = 73%
The E grade is high 30/60 = 50%

Its a good paper if you are an A/B student - its not so good if you are a CDE student.

UMS marks get stretched at the top and squashed at the bottom.


I am having difficulty revising for this. What do you think is the best way to revise since there are very little past papers for this. :s-smilie:
Reply 88
Avatar for Ralphus J
Ralphus J
Can someone test me? please
Reply 89
Avatar for Ralphus J
Ralphus J
Is kinetic model of a gas same as the assumptions.......

1. elastic collisions between particles and container
2. no intermolecular forces
3. total volume occupied by particles is negligible compared to total volume of container
4. constant rapid random collisions.
The Kinetic model is the description / calcualtion of how gas pressure derives from molecular collisions with the walls of the container.
Original post by Ralphus J
Can someone test me? please


We should test each other.

Define gravitational field strength... (I hate this one)
Reply 92
Avatar for getz123
getz123
Original post by shorty.loves.angels
We should test each other.

Define gravitational field strength... (I hate this one)

Gravitational field strength is the gravitational force per unit mass acting at a given point.
Original post by getz123
Gravitational field strength is the gravitational force per unit mass acting at a given point.


Now you give on for someone else to answer yeah?




Wait, isn't it Friday?

Wow, I really need to get a life.
Reply 94
Avatar for Ralphus J
Ralphus J
Original post by shorty.loves.angels
We should test each other.

Define gravitational field strength... (I hate this one)


force produced per unit mass in a gravitational field.

define angular frequency
Reply 95
Avatar for abu125
abu125
I am a bit confused on damping, does amplitude change or frequency?
Thanks
Original post by Ralphus J
force produced per unit mass in a gravitational field.

define angular frequency


Erm, frequency? I can only explain angular displacement in terms of velocity :sad:

Original post by abu125
I am a bit confused on damping, does amplitude change or frequency?
Thanks


The amplitude decreases. Pretty sure that frequency is only affected by mass? Or something? For example, the frequency/ time period isn't dependant on displacement, so although the amplitude is reducing, the frequency stays the same.

Definitely check the displacement/ time graph for damping :smile:

Someone please correct any of this :yy:
Reply 97
Avatar for wibletg
wibletg
3
Original post by shorty.loves.angels
Erm, frequency? I can only explain angular displacement in terms of velocity :sad:



The amplitude decreases. Pretty sure that frequency is only affected by mass? Or something? For example, the frequency/ time period isn't dependant on displacement, so although the amplitude is reducing, the frequency stays the same.

Definitely check the displacement/ time graph for damping :smile:

Someone please correct any of this :yy:


Angular frequency is 2pi times the frequency :tongue: daftest definition ever.

and amplitude does only decrease with damping in SHM.

Damping only ever affects the frequency during resonance (the resonant frequency shifts to the left very slightly) :smile:
Reply 98
Avatar for Ralphus J
Ralphus J
Original post by wibletg
Angular frequency is 2pi times the frequency :tongue: daftest definition ever.

and amplitude does only decrease with damping in SHM.

Damping only ever affects the frequency during resonance (the resonant frequency shifts to the left very slightly) :smile:



Your definition is correct i think, but i remember it as the rate of change of angle in radian per second.

and ye during damping of SHM decreases the frequency at which resonance takes place
Original post by wibletg
Angular frequency is 2pi times the frequency :tongue: daftest definition ever.

and amplitude does only decrease with damping in SHM.

Damping only ever affects the frequency during resonance (the resonant frequency shifts to the left very slightly) :smile:


Why did I not know that?? Grr, not gona forget it now!

Original post by Ralphus J
Your definition is correct i think, but i remember it as the rate of change of angle in radian per second.

and ye during damping of SHM decreases the frequency at which resonance takes place


Argh you lot are making me panic about this exam.

I'm doing a past paper tonight :colonhash:

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