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IGCSE Physics - 1P - 14th May 2013

Anyone have a good explanation as to why objects like feathers fall more slowly that objects like hammers and coins? I initially thought it was something to with surface area but I think it is more along the lines of terminal velocity.

I wouldn't call my explanation detailed but it should be sufficient to boost your understanding.
Feathers, to start with have a very low mass compared to hammers therefore it takes a very short time for it to reach terminal velocity. Also air resistance is able to act quicker on the feather due to its low mass. With the hammer it's the opposite.

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Reply 61

Themodfather

Original post by sa97

Isn't it 90 raw marks? (60 for reading and writing and 30 for listening). My teacher said that grade boundaries for the A* would be somewhere in the high 70's. It was 72 last year and 81 the year before I think.

I can show you the link where i get my information, i know it is 90 raw mark, so i am a bit miffed

http://www.edexcel.com/iwantto/Documents/1206%20International%20GCSE%20Grade%20Boundaries%20replacement.pdf

Reply 62

edstudent97

Original post by TheGrillMan

Hey there guys,

I thought I'd get in early and start a thread for this exam.

It should be a decent paper, assuming it's not like the January 2012 papers! (For those who have not completed them, they were so unbelievably... weird... that the overall grade boundary was 119/180 rather than the usual ~140/180).

Any topics you guys are worried about?

Peace.

i hope there aren't any tough questions regarding electromagnetism and stuff! i suck at that :frown:

Reply 63

parasagarwal01

Original post by alexgr97

Hi guys,

1) When answering questions about pressure, and it asks you what assumptions you have made, do you say that the mass and temperature/volume remains constant, or the same?
2) Is a definition of refraction - the bending (changing speed or direction) of a wave as it passes through a medium of different density?
3) How do you define critical angle? There seems to be a variety of different answers in different mark schemes.

Cheers!

It depends if it's Boyle or pressure law,
Boyles law then it's temperature remains constant and pressure law is volume remains constant.
Refraction is the bending of waves as they travel through different transparent media.
Critical angle is the angle of incidence in the optically dense medium when the angle of refraction in the optical less dense medium is 90

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Reply 64

alexgr97

3

Original post by sa97

Anyone have a good explanation as to why objects like feathers fall more slowly that objects like hammers and coins? I initially thought it was something to with surface area but I think it is more along the lines of terminal velocity.

This came up in one of the past papers. It was 4 marks, and you had to say that the feathers had a lower mass, so it needs a smaller drag force, meaning it reaches terminal velocity earlier than the hammers/coins. Therefore, the average velocity is lower, meaning it falls slower.

Reply 65

sa97

2

Original post by parasagarwal01

I wouldn't call my explanation detailed but it should be sufficient to boost your understanding.
Feathers, to start with have a very low mass compared to hammers therefore it takes a very short time for it to reach terminal velocity. Also air resistance is able to act quicker on the feather due to its low mass. With the hammer it's the opposite.

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Thanks!

Reply 66

parasagarwal01

I have a really imp. Question.. For the graph of half life are the points supposed to be joined together with a ruler or free hand?

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Reply 67

arkajyotig

2

Original post by ForeverDay

Yes it does, thank you. But how do the alternating currents get created (how does the sound energy become electrical energy)?

its the same thing but the opposite way:-
when we speak, the air vibrates which makes some cone or diagphram inside the microphone to vibrate causing the coil of wire attached to it to also vibrate. since the coil is surrounded by a magnet, the coil cuts the magnetic feild at right angles thus causing a voltage to be induced in the coil (electromagnetic induction). this induced voltage is alternating in nature becuz the coil moves forwards and backwards (as the diagphram vibrates) hence an A.c. to set up. i guess thats wat you wanted to know.

Reply 68

dathtom

14

Original post by parasagarwal01

I have a really imp. Question.. For the graph of half life are the points supposed to be joined together with a ruler or free hand?

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Free hand because it decreases exponentially. It's a curve.

Reply 69

amalik_

Forces on a beam, I'm able to work this out using my knowledge of maths and logic but is there a straightforward equation or anything which would be a more reliable method to use?

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Reply 70

sa97

2

Original post by Themodfather

For future plans, have you got any stock phrases?

I always try to use these when talking about future plans:

A l'avenir... (In the future)
chercher (to search/seek)
poursuivre (to pursue)
esperer (to hope)
Quand + future + future
J'aurai besoin (I will need)

Reply 71

alexgr97

3

Original post by amalik_

Forces on a beam, I'm able to work this out using my knowledge of maths and logic but is there a straightforward equation or anything which would be a more reliable method to use?

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For a system in equilibrium, the sum of the anticlockwise moments = the sum of the clockwise moments. That's all you can really say. As long as you know one side balances the other, then there's not much else.

Reply 72

sa97

2

Original post by amalik_

Forces on a beam, I'm able to work this out using my knowledge of maths and logic but is there a straightforward equation or anything which would be a more reliable method to use?

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Not in paper 1 just incase you didn't know.

Reply 73

amalik_

Okay thanks guys

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Reply 74

sa97

2

Anyone have three points in which the orbit of a comet differs from that of a planet:

1) elliptical
2) gets really close to sun and then goes far out
3) ????

Reply 75

amalik_

Also any complicated methods etc you'd suggest learning off by heart? I've learnt the process of the loudspeaker, electric motor, electric bell and explanations about how radioactive carbon dating works.

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Reply 76

alexgr97

3

Original post by sa97

Anyone have three points in which the orbit of a comet differs from that of a planet:

1) elliptical
2) gets really close to sun and then goes far out
3) ????

Constant time period i.e. the same amount of time to complete the orbit.

Reply 77

parasagarwal01

Guys.. Please check my Sankey diagram after reading the question. I have drawn it in proportion to the power values. Sorry I have to re edit this post but how do I upload a picture?

Reply 78

sa97

2

Original post by alexgr97

Constant time period i.e. the same amount of time to complete the orbit.

Thanks!!

Reply 79

dathtom

14

Original post by sa97

Anyone have three points in which the orbit of a comet differs from that of a planet:

1) elliptical
2) gets really close to sun and then goes far out
3) ????

Sun is not central.

IGCSE Physics - 1P - 14th May 2013

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