OCR ADVANCING PHYSICS B G494 EXAM MONDAY 18th June

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Good luck with the exams everyone! I personally haven't started revising for this exam yet as I have my more important exam afterwards :frown:

So dreading both of these. Gonna start my revision around midnight

Reply 121

silvertear

Why is momentum measured in N kg^-1?

Reply 122

lukas1051

Original post by silvertear

Why is momentum measured in N kg^-1?

I'm pretty certain it isn't... gravitational field strength is measured in that (from g = F/m) but momentum is either kg·m·s^-1 (from p = mv) or N·s (from Δp = FΔt)

Reply 123

silvertear

Original post by lukas1051

I'm pretty certain it isn't... gravitational field strength is measured in that (from g = F/m) but momentum is either kg·m·s^-1 (from p = mv) or N·s (from Δp = FΔt)

Thank god for that, I was starting to panic about momentum being different to what I thought it was..

Reply 124

EricEdwardSelvaraj

Original post by xiyangliu

Hi Dude

You are given a = - 50x. Therefore u can work out the acceleration at that displacement. S = 0.21 Take v = 0.85 as your initial speed. a is negative They give u time is 0.05. So now Use suvat. I think ..
:smile:

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This was posted from The Student Room's iPhone/iPad App

Thanks that was really helpful. I hate mechanics, so I don't like it when they sneak it in. I never know - unless stated- which is the initial and final speed.

Reply 125

PhysicsGirl

Original post by Revent

Good luck with the exams everyone! I personally haven't started revising for this exam yet as I have my more important exam afterwards :frown:

So dreading both of these. Gonna start my revision around midnight

Thank you :-) Good luck to you too!
If you're pulling a last minuter, I'd recommend the June 11 paper as a fairly standard paper to do.

Reply 126

EricEdwardSelvaraj

Original post by Smurfatar

This exam may be a tough one seeing as we were taught half of it by amazing teachers back in June/July 2011 and then they left and we got horrific ones up until Christmas. (I also realised this morning that, regardless of being taught it since yr10 or maybe even earlier, I have never actually understood Redshift and the Doppler Effect until this morning. I do worry myself sometimes) I genuinely taught myself the majority of the syllabus over the last couple of day by just reading every single word in the textbook. Most people slate it and admittedly, it is pretty rubbish if you're trying to find specifics, but damn, it's a Godsend if you read it through (and genuinely quite interesting! I don't seem to get into subjects until I properly revise them the week before my last exam xD ) Just thought i'd put that out there as I feel the need to procrastinate in a way which makes me feel like I am revising!
Hopefully this paper wont be dramatically hard, although low grade boundaries would be good! The wordy questions are going to trip me up the most though (also running out of time seems to be a key theme with my exams recently)
Anyway, since that is off my chest i'll go back to procrastinating by staring at beardy physicists in the textbook or reading 'witty anecdotes' from CGP (tehehehe)
Good luck all! And if anyone actually felt the need to read this, then you are time wasting my friend! (Although you may have assumed it would be helpful, in that case I will take a small amount of the blame) But still, get back to work!! This will all be over in less than a day :biggrin:

Looks like you did good. Can you please tell me what definitions you got for doppler effect and redshift?

Someone previously said redshift is the increase of wavelength, but that specifically applies to CRS.

I generally include three points for red shift: When an observer sees light that

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receding from him,

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increasing in wavelength [list]

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toward the red end of the spectrum.

Reply 127

PhysicsGirl

Original post by EricEdwardSelvaraj

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receding from him,

•

increasing in wavelength [list]

•

toward the red end of the spectrum.

Doppler shift happens when you have a moving object (relative to the stationary observer) that's emitting radiation, or a noise, or some kind of waves. If the object is moving away from the observer, the time between peaks increases and the wavelength increases, and vice versa if the object is moving toward the object :-) Redshift is a similar concept, expect it refers specifically to the spectrum emitted by various stellar objects that will be either red-shifted or blue -shifted due to the Doppler effect.

Reply 128

Revent

Original post by PhysicsGirl

Thank you :-) Good luck to you too!
If you're pulling a last minuter, I'd recommend the June 11 paper as a fairly standard paper to do.

Haha thanks :p:

Will look at it :smile:

Reply 129

Rotravis

Why is force J m^-1? I feel really stupid for asking this but my brain can't work out anything more today.

Reply 130

Oromis263

Original post by Rotravis

Why is force J m^-1? I feel really stupid for asking this but my brain can't work out anything more today.

Using the equation:

Work done = Fx, where the units are
Work done, J
x, displacement, m
Thus F, force is J/m (or a N)

:smile:

Reply 131

Dhanu123

I hate capacitors with a passion >.<

Reply 132

Miller693

Gonna go catch some Zs now, so good luck for tomorrow everyone. Oh and happy dreaming about simple harmonic oscillators and capacitors and everything else on this module. :smile:

Reply 133

lukas1051

Which red-shift/Doppler effect formulas do we need to know? There are loads in the textbook, some tied in with relativity. Is z = change in wavelength/wavelength all we need to know?

Reply 134

Rotravis

Original post by Dhanu123

I hate capacitors with a passion >.<

This. The jan 2012 capacitor questions were okay, but I can't think to imagine what hellish questions we'll get tomorrow.

GOOD LUCK EVERYONE!

Reply 135

Anthony Soprano

Hey, anyone have a link to the Jan 2012 mark scheme please?

Reply 136

7ay7ay

Original post by Anthony Soprano

Hey, anyone have a link to the Jan 2012 mark scheme please?

Look back at page 3/4 and there should be a link :smile:

Good luck guys!

Reply 137

Anthony Soprano

Original post by 7ay7ay

Look back at page 3/4 and there should be a link :smile:

Good luck guys!

Yep, found it, thank you very much.

Good luck to you too

Reply 138

Amy-Rose

Can anyone explain why a small temperature increase leads to large difference in rate? (Boltzmann factor)

Reply 139

freakymonkey

Original post by Amy-Rose

Can anyone explain why a small temperature increase leads to large difference in rate? (Boltzmann factor)

When T increases, E/kT decreases, so e^-E/kT tends to zero, but since there is an 'e' term in there a small change in T makes e^-E/kT increase dramatically.

Important thing to note, when E=kT, e^-E/kT = e^-1, so if they ask you to graph how the Boltzmann factor changes with temperature, make sure that when E=kT the graph goes through the point y=e^-1, so roughly 1/3.

If you have any further questions please ask. And good luck tomorrow morning :smile:

(edited 11 years ago)