Physics, Chemistry and Biology: Post your doubts here!

[Z.A.M]

Is there a really difficult or tricky question that anyone has gone through please post here I wana try everything incase I've missed

 

[EpicLol]

HELP ASAP

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s09_qp_3.pdf
Variant 2
Question 5b (ii)
Question 11 b. How do you get it?

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s10_qp_32.pdf
Question 2c
Question 11 b.

11b Im not sure as well....its a hard question....

 

[Moi]

area wont double, it will b multiplied by 4!!!

Why when we half it , it multiply by 4 ?? I don't get it

 

[ZainH]

NO. he still speeds up but at a smaller rate.

If your speeding up at a slower rate, your OVERALL speed is technically decreasing :S

 

[Z.A.M]

NO. he still speeds up but at a smaller rate.

Yes u r rite acceleration is the rate of change of speed so his speed may be increasing but he's accelerating

He decelerates when his speed decreases or hes goes in opposite direction

 

[semsemhosam]

frequency = velocity/wave length..........which is equal to 240/1.95*10 to the power of 5............which is equal to 1.23* 10 to the power of negative 3 HERTZ

(240)/(1.9 x 10^5)=1.26 x 10 ^ -3

 

[AAnsarii]

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s10_qp_32.pdf
Q NO 10 (A ) AND (B) IN THE ABOVE PASTPAPER ATTACHED LINK !!!! PLZ HELP ME ....THNX IN ADVANCE

10(a)
frequency is multiplied by 1.5, so freq(no of waves, ie 2) * 1.5= 3, so u'll have 2 draw 3 waves, these need 2 b equally distributed, so u count no of horizontal lines (6) divide it by 3, which gives 2, so every upper half of d wave will have 2 cm, as will d lower half.
(b) now u wanna halve d height, so dats to do wid voltage/cm, n not wid d time base, so rite no change in time base
d cm stays, n u decrease d height, so increase d voltage, so it'll take up lesser space, n do so by 2, ie make 5 v/cm 10 v/cm

hope u got it
All d best

 

[EpicLol]

But why when diameter halfed, area increased by 4 ???
and why you multiplied the old resistance with the area in specific ??

when diameter becomes half, its half of original area, so inverse of it would be *2 therefore its 2*2 = 4....

 

[AAnsarii]

I understand better now but I have 1 question why is pie r^2 would be 2^2 and 4? why is it 4*4?
I do understand that area decreases and resistance increases....so....plz help sorry if Im annoyinh u

c u calculate d area when u do pie r square n u further multiply dis by 4 coz it was d earlier value of resistance 2 get resistance of the thinner wire of the same length
no im not annoyed, help others 2 help urself

 

[Z.A.M]

If your speeding up at a slower rate, your OVERALL speed is technically decreasing :S

No dude ur speed can be increasing but the rate at which it's increasing can slow for eg a car increases his speed from 2 to 8 m/s in only 4sec but now he increases his speed from 8 to 10 in 4 sec this means he only increased his speed by 2 in 4 sec so his acceleration decreases yet his speed does increase at slower rate

 

[ZainH]

no ........its slowly increasing...........eg- acceleration was 2.5 ms squared ok, so ur speed increases by 2.5 ms evry second, then acceleration decreases to, for example, 1ms squared, so ur speed increases, but only by 1 ms every second

Wow I'm sorry.. lol I don't know WHY I am still online.
Starting to mix up simple things now.. ugh.. yeah your right , my bad x(

 

[shafayat]

what is the difference between the accelerating anode and the focusing anode in the cathode ray ossiloscope????

accelerationg anode only accelerates the electrons ... it has high dc voltage connected across it ! focuscing anode makes the electrons in a beam ! usally they both r intergrated n made into one

 

[Z.A.M]

ye
YEA...ME N U STUDY LIKE A BOSS

 

[AAnsarii]

How many S.f round our answers to ?

whatever u feel like

 

[Z.A.M]

whatever u feel like

No dude better to give it to 3 or 2 decimal places

 

[Z.A.M]

Asking once again has anyone cum across a really difficult question I wana solve it incase I've missed pleaseee

 

[AAnsarii]

No dude better to give it to 3 or 2 decimal places

thnx 4 d info
all d best evy1

 

[Moi]

u need 2 noe dat resistance is directly proportional 2 length: l increases so r increases, & resistance is invrsly proportional 2 area, area decreases, resistance increases.
diameter is halved, so (hope u nderstand dis.) by pie r^2, area will b multiplied by 2^2 = 4. {the 2 is here coz u halved d diameter}


so resistance increases to 4*4, = 16 ohms.

now refer 2 d qn, they have current as 0.3A, so actually the resistance= v/i = 1.8/0.3 = 6 ohms
so 4 d ratio, u do resistance of what u need, the actual 1: resistance of r calculated hypothesis, which assumes original length.
= 6/16 =0.375

hope u understood, i noe im a horrible xplainer, n refer to ms, its v helpful.
all d best

but we don't know the diameter inorder to know how much it'll be after it halfed, so why you put the radias as 2 ??

 

[AAnsarii]

Asking once again has anyone cum across a really difficult question I wana solve it incase I've missed pleaseee

dunno idf its diff but plz xplain 9 (c)(i) , also they've given valur in Kelvin n not C , what 2 do?

 

[AAnsarii]

but we don't know the diameter inorder to know how much it'll be after it halfed, so why you put the radias as 2 ??

in the QN its mentioned dat diameter is halved!!! so radius inverse of 1/2 is 2? u then square it 2 NOE THE RESISTANCE.
hope u got it.