Physics: Post your doubts here!

[Rizwan Javed]

where did you get that from?

idk, it was some strange website :S Wait let me share this book here.

 

[My Name]

I got one :3

Is thhis for the 2016 syllabus?
Did you put it up on gceguide yet?

 

[Eugene99]

idk, it was some strange website :S Wait let me share this book here.

you know that strange website doesn't open in Pakistan!

 

[Eugene99]

I think CIE is going to sue us for all the ebook priating! The publishers won't be happy and it means a lot of loss for them

 

[Rizwan Javed]

Is thhis for the 2016 syllabus?
Did you put it up on gceguide yet?

http://gceguide.com/Books/Cambridge International AS and A Level Physics 2nd ed.pdf

It is for 2016 syllabus

Not yet. Too lazy

you know that strange website doesn't open in Pakistan!

O.O what're you talking about?

I think CIE is going to sue us for all the ebook priating! The publishers won't be happy and it means a lot of loss for them

I didn't scan them. I'm just sharing the ones i downloaded from other websites.

 

[My Name]

Eddy currrents,Faradays disc,search coil,bainbridge spectrometer.
These arent there for 2016 right?

 

[Rizwan Javed]

Eddy currrents,Faradays disc,search coil,bainbridge spectrometer.
These arent there for 2016 right?

I don't know.

 

[qwertypoiu]

Eddy currrents,Faradays disc,search coil,bainbridge spectrometer.
These arent there for 2016 right?

If you look at the syllabus and scroll to the last page you'll see all removed content.

 

[Saad the Paki]

I have posted the complete question for reference. But what I'm confused about is (b) (ii). According to the ms the new line will be below the original line reaching terminal velocity in shorter time. But if the sphere has a smaller radius thus a smaller surface area, the effect of air resistance will be less so it will take more time to reach terminal velocity.

 

[qwertypoiu]

View attachment 59797 View attachment 59798
I have posted the complete question for reference. But what I'm confused about is (b) (ii). According to the ms the new line will be below the original line reaching terminal velocity in shorter time. But if the sphere has a smaller radius thus a smaller surface area, the effect of air resistance will be less so it will take more time to reach terminal velocity.

If a raindrop is falling through air, we can think of two forces acting on it:

1. W, the weight. This makes the raindrop fall down. W is directly proportional to mass of raindrop. The mass of raindrop is directly proportional to its volume. And the volume is directly proportianal to its radius CUBED. Therefore, W is proportional to raindrop's radius CUBED.
2. F, the frictional force. They told us in the question (in the form of a formula) that this force is directly proportianal to radius. (To power one)

So when radius is reduced, both W and F will be reduced. However, W will be reduced MORE.

When the raindrop falls, its velocity increases so F increases and, at one point, W is completely countered and so the drop is in terminal velocity.
If W is very little (like in our case) it takes a shorter time for F to counter balance the W.

 

[Saad the Paki]

If a raindrop is falling through air, we can think of two forces acting on it:

1. W, the weight. This makes the raindrop fall down. W is directly proportional to mass of raindrop. The mass of raindrop is directly proportional to its volume. And the volume is directly proportianal to its radius CUBED. Therefore, W is proportional to raindrop's radius CUBED.
2. F, the frictional force. They told us in the question (in the form of a formula) that this force is directly proportianal to radius. (To power one)

So when radius is reduced, both W and F will be reduced. However, W will be reduced MORE.

When the raindrop falls, its velocity increases so F increases and, at one point, W is completely countered and so the drop is in terminal velocity.
If W is very little (like in our case) it takes a shorter time for F to counter balance the W.

So you're saying if I have 2 steel balls one the size of a football and other the size of a tennis ball, the tennis ball will reach terminal velocity first?

 

[qwertypoiu]

So you're saying if I have 2 steel balls one the size of a football and other the size of a tennis ball, the tennis ball will reach terminal velocity first?

Yes!

 

[Saad the Paki]

Yes!

OK wow well that doesn't seem practically correct but thanks anyway.

 

[holoholo]

Can someone explain to me how the 240 is the root mean square speed ? And why we have to multiply it by root of 2 ?

 

[Akshajistari]

View attachment 59839

Can someone explain to me how the 240 is the root mean square speed ? And why we have to multiply it by root of 2 ?

I think you meant root mean square voltage

Well, the formula is usually Vrms=Vo/square root of 2

When the voltage of an alternating current is given without any other detail, it is assumed to be the Vrms.
And since you are comparing to a value that is a peak voltage(9.0V) you have to convert the 240 to peak value too.
So Vo=Vrms*square root 2

Hope I helped.

 

[holoholo]

I think you meant root mean square voltage

Well, the formula is usually Vrms=Vo/square root of 2

When the voltage of an alternating current is given without any other detail, it is assumed to be the Vrms.
And since you are comparing to a value that is a peak voltage(9.0V) you have to convert the 240 to peak value too.
So Vo=Vrms*square root 2

Hope I helped.

Yes thank you
Can you please explain sampling frequency ?

 

[Mayarzawaydeh]

hey does anyone know on what bases do we get our candidate numbers? I mean where does the count start from ( if that makes sense hahah)

 

[Mayarzawaydeh]

Try at gcecuide

thanks!!

 

[Akshajistari]

Yes thank you
Can you please explain sampling frequency ?

Sampling frequency as in the one in Communications?

 

[The Sarcastic Retard]

Yes thank you
Can you please explain sampling frequency ?

http://www.fon.hum.uva.nl/praat/manual/sampling_frequency.html