You are Here: Home >< Physics

# OCR Physics A G484: 20th June 2016 watch

1. Can someone explain brownian motion to me and what the thing showed?
2. (Original post by Timon512)
Place all of the apparatus in the thermally insulated container with a lid. Use an electronic mass balance to measure and record the mass of liquid in the beaker. Place thermometer into liquid to measure the initial temperature or you can use a temperature sensor and datalogger. Attach an Ammeter in series and a Voltmeter in parallel to an ELECTRICAL heater. Using an electronic stopwatch, measure the time taken for a given temperature rise. Change in temperature = Tf - Ti. As P=IV, W=IVT and as W=MC^T, C = W/M^T = IVT/M^T.
Just a quick follow up sorry, would you use a variable resistor to get different values for I and V (and also t with the stopwatch) to get multiple c values from which an average can be found? I've seen that in the past on revision websites but I'm not sure if we have to go into that much detail for this exam.
3. (Original post by tobibo)
Just a quick follow up sorry, would you use a variable resistor to get different values for I and V (and also t with the stopwatch) to get multiple c values from which an average can be found? I've seen that in the past on revision websites but I'm not sure if we have to go into that much detail for this exam.
No there is no need for this. You are only using the I and V to work out how much thermal energy you have transferred. If you varied I and V you would get a tying amounts of the meal energy, varying changes of temoerature and varying values of C - so not in this case...
4. Anyone know how to get the June 2015 paper and markscheme?
5. For the paper: http://www.thestudentroom.co.uk/show...3670959&page=3

Question:
June 14 Q 3b ii) Why does the KE drop to 1/4 if height from which is dropped is halved?Wouldn't it also be halved?
6. Can someone please help me understand moles further. I know that n = mass / molar mass, and number of particles = n * Na.
What else do I need to know. Thanks.
7. (Original post by ukcolBehT)
Question:
June 14 Q 3b ii) Why does the KE drop to 1/4 if height from which is dropped is halved?Wouldn't it also be halved?
Thanks for the paper.

I think they expected us to use the equation Vmax = (2pif)A
so if amplitude halves, max velocity halves and max KE decreases to 1/4.
8. Anyone understand Jan 2011, question 2(c)(i)? I understand the idea of a force due to mass being ejected, but why are we applying a decelerating force to move the satellite into a smaller orbit? In (ii), we work out the speed of the satellite increases when the orbit radius decreases, so surely you need an accelerating force to get a smaller orbit? Can anyone help?
9. (Original post by AlexeiLipov)
Anyone understand Jan 2011, question 2(c)(i)? I understand the idea of a force due to mass being ejected, but why are we applying a decelerating force to move the satellite into a smaller orbit? In (ii), we work out the speed of the satellite increases when the orbit radius decreases, so surely you need an accelerating force to get a smaller orbit? Can anyone help?
According to F = GMm / r2
If GMm is constant, F is proportional to r2, so if we want smaller orbit (basically smaller r) we need to increase the force, also because if you rearrange r2 will be equal to GMm / F.
10. (Original post by Super199)
Can someone explain brownian motion to me and what the thing showed?
It proves ideal gas assumptions.
Equipment: Light source, closed smoke cell, microscope.

If you look through microscope:
-You will see specks of light that are moving in continous random motion due to continues collisions with gas molecules.

Conclusions:
- Smoke paricles (what we see) are larger than gas particles (what we cant see)
-Random motion of smoke particles means gas particles are moving with random motion.
-Continous motion of smoke particles means gas particles has continous motion.

Hope this helps.
11. Do we need G485 content for this exam?
12. Can someone help me with conversions from things like molar mass into mass, moles and all that because it's really confusing me
13. Never seen anything on damping in past papers, maybe this is the year for it?
14. (Original post by Tizzydag)
Never seen anything on damping in past papers, maybe this is the year for it?
yeah there has been one or two things, like drawing on a graph what it looks like

There's not much they can ask really. The could ask about the experiment with the spring and card but thats it really
15. (Original post by EpicTree)
Can someone help me with conversions from things like molar mass into mass, moles and all that because it's really confusing me
If you are given molar mass = 4.0 g mol-1 then mass of 1 molecule will be

m = 4.0 x 10-3 / Na

And number of moles = mass / molar mass
And # number of molecules = # moles * Na
16. Can someone note the pressure laws/ equations

Isn't like p1v1/T1 = p2v2/T2

are there any others?
17. can someone give me the definition of 'angular frequency', can't find it in my book. thank you
18. (Original post by EpicTree)
can someone give me the definition of 'angular frequency', can't find it in my book. thank you
Change in angle per unit time. 2pi x frequency
19. can someone remind me what the equations Asin(2 x pi x f x t) and Acos(2 x pi x f x t) is used for?
20. Can someone explain 2bii

https://6d58568f77fa37b9c685ab8ce928...%20A-level.pdf

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: June 20, 2016
Today on TSR

### 2,526

students online now

Exam discussions

### Find your exam discussion here

Poll
Useful resources

Can you help? Study help unanswered threadsStudy Help rules and posting guidelinesLaTex guide for writing equations on TSR

## Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE