A2 (Edexcel) Physics Unit 4 & 5 6PH08 June 2012

Yep as far as I have heard CIE BIo and Chem is easier than edexcel but when it comes to physics and maths...edexcel boeard is easier...

Reallyy!? Easier! Wow. Ughh. I just wanna get Edexcel over with :P

Reply 101

EllaBella<3

12

Hello

I was hoping somebody could explain to me how you prove/explain a glancing collision?

Thank you! :biggrin:

Reply 102

Omar1994

they can ask some really stupid questions sometimes that have nothing to do with the syllabus !

Reply 103

d_94

7

Original post by Omar1994

they can ask some really stupid questions sometimes that have nothing to do with the syllabus !

Truee

Reply 104

lipton600

Hey ,, anyone here kind enough to explain to me a question..UNIT 4
There's a past year question regarding electromagnetic induction ...about the bicycle wheel and the spokes moving in a clockwise direction..

I'm not sure what year is it from,,

(i) Label the hub and rim either plus or minus to show the polarity of the e.m.f.

Answer is HUB "-" and rim "+"...

I don't understand that,,, if you use flemings right hand,,, don't you get otherwise?

Thanks for taking time to read

Reply 105

Parthenon93

7

Original post by lipton600

Hey ,, anyone here kind enough to explain to me a question..UNIT 4
There's a past year question regarding electromagnetic induction ...about the bicycle wheel and the spokes moving in a clockwise direction..

I'm not sure what year is it from,,

(i) Label the hub and rim either plus or minus to show the polarity of the e.m.f.

Answer is HUB "-" and rim "+"...

I don't understand that,,, if you use flemings right hand,,, don't you get otherwise?

Thanks for taking time to read

Year and question no. please?

Reply 106

Antimony

Original post by lipton600

Hey ,, anyone here kind enough to explain to me a question..UNIT 4
There's a past year question regarding electromagnetic induction ...about the bicycle wheel and the spokes moving in a clockwise direction..

I'm not sure what year is it from,,

(i) Label the hub and rim either plus or minus to show the polarity of the e.m.f.

Answer is HUB "-" and rim "+"...

I don't understand that,,, if you use flemings right hand,,, don't you get otherwise?

Thanks for taking time to read

Basically use flems right hand rule where where you point first finger into paper, the thumb points to the right and the second finger points towards the positive polarity of the induced emf

I asked the same question :P follow the link for a full explanation
http://www.thestudentroom.co.uk/showthread.php?t=2013003

Reply 107

Parthenon93

7

Original post by Antimony

Basically use flems right hand rule where where you point first finger into paper, the thumb points to the right and the second finger points towards the positive polarity of the induced emf

I asked the same question :P follow the link for a full explanation
http://www.thestudentroom.co.uk/showthread.php?t=2013003

I am a bit confused. I used the right hand rule to get induced towards the rim. So shouldn't rim be negative? Isn't conventional current from positive end of battery to negative end of battery? :/

Reply 108

Ifrahim

Two loops, A and B, are aligned parallel to each other. There is a current in loop A, which induces a current in loop B. How does the current in loop A change with time?
guyssss need help with it.........

Reply 109

Parthenon93

7

Original post by Ifrahim

Two loops, A and B, are aligned parallel to each other. There is a current in loop A, which induces a current in loop B. How does the current in loop A change with time?
guyssss need help with it.........

Induced current in loop B should oppose the current in loop A. Also larger the current in loop A, larger the current in loop B - current in loop A is proportional to current in loop B. So I guess the current in loop A will fall exponentially with time.

(edited 11 years ago)

Reply 110

username287755

Original post by Parthenon93

I am a bit confused. I used the right hand rule to get induced towards the rim. So shouldn't rim be negative? Isn't conventional current from positive end of battery to negative end of battery? :/

im confused about the same thing..

Reply 111

iesians

6

question for unit 5

why is a ball bouncing on a hard surface NOT an example of SHM ..?

Reply 112

Parthenon93

7

Original post by iesians

question for unit 5

why is a ball bouncing on a hard surface NOT an example of SHM ..?

Probably because the oscillation is damped. I am assuming it isn't isochronous either - time period not constant. So even though acceleration ∝ - displacement, it isn't a periodic motion.

For SHM you have two conditions: 1. periodic motion 2. a ∝ -x.

Reply 113

Parthenon93

7

Original post by Killerstorm2

im confused about the same thing..

Stongebridge cleared it up for me yesterday.

We are thinking of the stoke as a battery, but it is not.

In a battery the electrons are prevented from directly flowing through the battery - and so have to go externally through a wire.

In the stoke the electrons will flow internally through the stoke.

So the polarities appear opposite.

Since direction of induced current - i.e. direction of positive charge - is from hub to rim, the electrons must flow from rim to hub. The collection of electrons at the hub makes it negative.

Reply 114

iesians

6

Original post by Parthenon93

Probably because the oscillation is damped. I am assuming it isn't isochronous either - time period not constant. So even though acceleration ∝ - displacement, it isn't a periodic motion.

For SHM you have two conditions: 1. periodic motion 2. a ∝ -x.

WHAT ?!
almost every oscillation is damped !

Reply 115

uuuuu

in unit 4 when a capacitor charge's/discharges do the current and voltage or anything else also change :confused:

Reply 116

DarrenDM

Q10b

Shouldn't the bottom plate be - and top plate be +? (Not the other way round as stated in MS)

Physics Unit 4 - Jan 10 QP.pdf542.1KB

Reply 117

cjcmoney

Original post by DarrenDM

Q10b

Shouldn't the bottom plate be - and top plate be +? (Not the other way round as stated in MS)

The MS is talking about the molecules.... not the plates. the plates would be - on bottom and + on top but obviously the molecule - charge would be at the top attracted to the + plate

Reply 118

DarrenDM

Original post by cjcmoney

The MS is talking about the molecules.... not the plates. the plates would be - on bottom and + on top but obviously the molecule - charge would be at the top attracted to the + plate

Oh thanks! Misread it.

That's exactly what I thought, cheers.

Reply 119

meraphox

Original post by Parthenon93

Lol yes, but the oscillations you are considering are oscillations of very small amplitudes (4') and are only lightly damped by air.

Bouncing ball has very large amplitude (large height) and is heavily damped - I think about 1/3 or 2/3rd of the energy is lost every bounce.

But I could be wrong ofcourse.

No ur right I had a question like this in my m2 book and had to calculate loss in height for every bounce it followed a series pattern

It all depends on coefficient of restitution of the ball

Ie snooker balls are more elastic in collisions than tennis balls

But when bouncing them on the ground it's other way round

Ugh things like this bother me so much lol
Most of the marks these days depend whether you can interpret their writing in the way they want you to :/

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

A2 (Edexcel) Physics Unit 4 & 5 6PH08 June 2012

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