You are Here: Home >< Physics

# Edexcel A2 Physics Unit 5 'Physics from Creation to Collapse' watch

1. (Original post by lefneosan)
why doesnt it increase the resonant frequency? surley a damped system should require more energy?
heres what i think. correct me if i am wrong
when you damp a system, the damper absorbs energy from the system. so the resonant amplitude of the system decreases. so as amplitude has decresed due to damping, less ennergy is needed and hence less frequency
2. (Original post by unamed)
I don't think so! I've not seen them in the Miles Hudson book, and I just looked through the specification - it's not there!
oh ok cool thanks
3. for the definition of half life, you have to say the "average" time taken for the nuclei to decay by 50% ?
4. (Original post by Kameo)
for the definition of half life, you have to say the "average" time taken for the nuclei to decay by 50% ?
No, since that's how you'd work it out in an experiment. But the actual definition is just the time taken for half the radioactive nuclei of a radioactive substance to decay.
5. (Original post by kosy91)
heres what i think. correct me if i am wrong
when you damp a system, the damper absorbs energy from the system. so the resonant amplitude of the system decreases. so as amplitude has decresed due to damping, less ennergy is needed and hence less frequency
I dno I partly agree but I dont think youve thought that through. Every amplitude is damped so every amplitude requires more energy to reach.
6. (Original post by unamed)
hope that clears it up!
The answer about the Doppler shift really does clear it up. Thanks a lot!

In the first question though, I was referring to the Wien's law spectrum, not the absorption spectrum.
7. (Original post by unamed)
No, since that's how you'd work it out in an experiment. But the actual definition is just the time taken for half the radioactive nuclei of a radioactive substance to decay.
from the markscheme, it has average in brackets so I guess you won't lose a mark if you put it in.
8. I can finally join this after doing FP3 *waves*

I hope this exam is not very difficult -_-
9. (Original post by OL1V3R)
The answer about the Doppler shift really does clear it up. Thanks a lot!

In the first question though, I was referring to the Wien's law spectrum, not the absorption spectrum.
Its kinda the same thing. You look at the spectrum of EM radiation you recieve from a star, find the most dominant wavelenght that is released of with the highest intensity/frequency. That frequency will tell you what colour the star appears. E.g. low wavelength = blue star, high wavelength = red star
10. (Original post by OL1V3R)
The answer about the Doppler shift really does clear it up. Thanks a lot!

In the first question though, I was referring to the Wien's law spectrum, not the absorption spectrum.
Yay!

Well, it's a a matter of which part of the visible wavelengths the max is closer to. (see attachment).

As, in my diagram, the star's max wavelength is close to the red-part of the visible spectrum (greater wavelength), it will appear redder.
Make sense?
Attached Images

11. (Original post by unamed)
Yay!

Well, it's a a matter of which part of the visible wavelengths the max is closer to. (see attachment).

As, in my diagram, the star's max wavelength is close to the red-part of the visible spectrum (greater wavelength), it will appear redder.
Make sense?
That makes perfect sense! Cheers mate!
12. can anyone explain the examzone answer for topic 4 #4b?? i dont get it...
http://www.thestudentroom.co.uk/show...9#post24561589
thank you!
topic 4 is thermal energy btw
13. (Original post by dimi3)
can anyone explain the examzone answer for topic 4 #4b?? i dont get it...
http://www.thestudentroom.co.uk/show...9#post24561589
thank you!
topic 4 is thermal energy btw
The rise becomes smaller as the heat is increasingly lost to the surroundings; the higher it becomes. Therefore the temp. itself does not increase as quickly.

14. hey guys....can you pls explain whats happening here ?

dont get it why the shapes like that
15. (Original post by ♥anonymousgangster)
hey guys....can you pls explain whats happening here ?

dont get it why the shapes like that
In what context is this? Is this in a wire?
16. (Original post by OL1V3R)
In what context is this? Is this in a wire?
beta decay of electrons....it seems energy is shared between electron , electron antineutrino and some to recoil the nucleus..... the book gives the same graph with hard to get explanation...
17. for barton's pendulum system, the other bobs have the same frequency as the driver but the one with the same length has a high amplitude like the driver?
18. (Original post by Kameo)
for barton's pendulum system, the other bobs have the same frequency as the driver but the one with the same length has a high amplitude like the driver?
No, the one with the same length as the same natural frequency as the driver - therefore moves with the greatest amplitude. The others show no/little movement.
19. Got a question for you guys,

A mass of 0.08kg suspended from a vertical spring oscillates with a period of 1.5s.
Calculate the force constant of the spring (2)
20. under boyle's law:

how do you plot the graph of pV against V???? and why??

### 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: March 27, 2015
The home of Results and Clearing

### 3,165

people online now

### 1,567,000

students helped last year
Today on TSR

### University open days

1. London Metropolitan University
Sat, 18 Aug '18
2. Edge Hill University
Sat, 18 Aug '18
3. Bournemouth University
Sat, 18 Aug '18
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