# A2 Physics | Post your doubts here

#### hassam

for 2 b iii
u know mass of ice melted in 10 min.....from this u cn find the mass of ice melted in 5 min just due to atmosphere....now subtract this value from 64.7 and apply Q=mLf

#### miss irfan

thanks hassam. can you answer the other two questions?
and from which website did you get the singapore pastpapers?

#### princesskt

for 2 b iii
u know mass of ice melted in 10 min.....from this u cn find the mass of ice melted in 5 min just due to atmosphere....now subtract this value from 64.7 and apply Q=mLf
WHY CANT MULTIPLY THE OTHER VALUE BY 2 (64.7*2)

#### SkyPilotage

I would sugguest, waiting for questions to be solved first then post more...Because you are pushing your old questions up and people may not notice it.. Thank you.
7 b) from the eqn in part a) , v= E / B . Since v , B , E are not changed. Then there is no deflection in the path of the alpha particle.
8 b) Whats going on here is that 120 nm is used for photoelectric effect. But they just put an extra lamp of frequecny 450 nm to produce more lighting to observe it better.
Therefore, you have to find the threshold wavelength , which will deduce that the 450 nm will have no effect on the photoelectric current since its greater than the threshold wavelenght or lesss thant the threshold frequency.
Question 2 c ii)
If it loses k.e then it loses speed, then radius becomes smaller. So final momentum / initial momentum = raio of small radius / larger radius = 0.77
8 a) for this you can use the atomic number as reference. You should also know position of uranium on their which is at far right.
use fleming left hand rule
6 c) I proportional to r , take ratios
7 c) http://www.electronics-tutorials.ws/diode/diode_6.html peak to peak ripple decreases
8 c) Total Binding energy of product - Total Binding energy of Reactants = 17.7 MeV
2 c ii) was canceled from mark scheme.
7 a) discrete wavelengths on screen ----> discrete photon energies from transition of energy levels ----> discrete energy levels
b ii) subtract energy levels to find energy so that it meets energy of photon.
9 c ii) D A C , check the table, binary digit inputs converted to decimals.
2 b) PV = nRT where n = (N / Na ) where N = Ne^-lambda x t !
4 b) differentiate to goet a = - w^2 r
6 c) 2.3 x root 2 = max mass change x 2 = variation from -ve peak to +ve peak. ( sinosoidal )
9 b) explained previously ubove in thread page 17-18
2 b iii) explained above
7 c) i ) smallest wavelenth = largest energy level transition!
PHEW! DONE AT LAST joking , took me 20 minutes

#### SkyPilotage

ok a simple questin here f= mv^2/r this means that centripital force is inversly proportional to radius??? ryt??

now here in this paper, question 1 c)
it is stated that centripital frce will increase as radius increases???
great confusion
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s08_qp_4.pdf
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s08_ms_4.pdf
two different formulas, mv^2 /r and m r w^2... depends on what you are using!

#### SkyPilotage

WHY CANT MULTIPLY THE OTHER VALUE BY 2 (64.7*2)
question was asking for 5 minutes!

now
her in question 6 part a) as the coil to be have maximum torque itx plane should be parralel to the magnetic field.

so it means that side AB or CD should be at the top and bottom creating a vertical plane ??

#### Abdulrab

ok a simple questin here f= mv^2/r this means that centripital force is inversly proportional to radius??? ryt??

now here in this paper, question 1 c)
it is stated that centripital frce will increase as radius increases???
great confusion
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s08_qp_4.pdf
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s08_ms_4.pdf
u will apply the formula f= mrw*2 not the you hav stated but we r talking about the angular acceleration so this equation is applicable here so according to this increse in radius mean centripetal force is also increased. I hope it helps you and clear your problem.

#### hateexamz

leadingguy nd SkyPilotage thank u so mch u guyz really are lifesavers nd nw i will let u guyz rest nd bring up more Qs tomorrow

Q1 (C)

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#### princesskt

CAN
to provide coverage at the poles!
U EXPLAINIT WHY??????????
FOR COVERAGE AT POLES 23 DEGREE IS THE ANGLE.....ISNT IT???

CAN
U EXPLAINIT WHY??????????
FOR COVERAGE AT POLES 23 DEGREE IS THE ANGLE.....ISNT IT???

As far as books and application booklet ix concerned they state away says that a geosationary satelite rotates on the equator and therefore itx nt possible fr it to cover polar regions. thatx the only reason polar satelites are used fr communication in those areas.

now if the sattelite is a little inclined so it may be possible fr it to send and recieve signalx at the top of the earth(polar region) as when we need to pick some thing from a higher position we stand on our toes(making an angle from ground) to have excess to that furthest position.

the m.s also states that having an inclination of 55 degrees make the gps able to reach to polar areas.

hope I am able to clear mY point oF VIEW

#### princesskt

As far as books and application booklet ix concerned they state away says that a geosationary satelite rotates on the equator and therefore itx nt possible fr it to cover polar regions. thatx the only reason polar satelites are used fr communication in those areas.

now if the sattelite is a little inclined so it may be possible fr it to send and recieve signalx at the top of the earth(polar region) as when we need to pick some thing from a higher position we stand on our toes(making an angle from ground) to have excess to that furthest position.

the m.s also states that having an inclination of 55 degrees make the gps able to reach to polar areas.

hope I am able to clear mY point oF VIEW
YEAH I UNDER STOOD THANKS....................
FOR EQUATOR ITS NECESSARY THAT IT IS IN LINE OF SIGHT...........

#### JohnChemistry

I need an A* in Physics A2, however my result at AS level was 86 in UMS. What grade do I need (more or less, cause its impossible to know specifically) in order to overcome the AS result and obtain one on the top 10%?

#### Abdulrab

guys i am really worried about medical physics i dont even know a bit about it can anyone please help me on it and guide me what to learn any important points and if anyone has made any good notes on it so please post it here !! thanks in advance waiting for the reply soon

#### JohnChemistry

guys i am really worried about medical physics i dont even know a bit about it can anyone please help me on it and guide me what to learn any important points and if anyone has made any good notes on it so please post it here !! thanks in advance waiting for the reply soon
In Remote Sensing (in the document I uploaded) you have everything you need - from page 14 to 26 I think

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#### Abdulrab

In Remote Sensing (in the document I uploaded) you have everything you need - from page 14 to 26 I think
thanks for it i know its in the app booklet but i need simple notes to learn them as it is very confusing in the application booklet

#### JohnChemistry

thanks for it i know its in the app booklet but i need simple notes to learn them as it is very confusing in the application booklet
With the application booklet I got some main ideas and then got to understand everything much better through answering past papers and then checking the mark-schemes...