Physics: Post your doubts here!

[Oliveme]

No, it would have been gravitational potential if I had used only mass of α nucleus. [potential = GM/R]
but since i used both the masses, it is gravitational potential ENERGY

diff btw electric potential energy n electric potential is the same
electric potential = electric potential energy / charge

Thank you very, very much gary221
I get it now.

 

[ZainH]

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Physics (0625)/0625_s12_qp_61.pdf

Please help me in the first question!! it is not As i just need to know how to draw

That's an IGCSE question, you're in the wrong board. This is for AS.

 

[asd]

righto
mass of a person = around 70kg
height of a person = 1.5m
density of water = 300 cm^3
weight of an apple = 1N
typical current in domestic appliances = 13 A
e.m.f of a car battery = 12 V
density of air at STP = 1.293 kg/m^3

since the wavelength and frequencies are related by V=freq. x wavelength, and since v of all E.M waves is 3.0 x 10^8
just remember one of them.. i'll put them up

Dont forget these (they're the ones that I came across while solving the past papers and are not mentioned in the book ) :
mass of a nucleus: 1*10^-25 kg
radius of a nucleus: From 1*10^-15 - (1*10^-14) m
radius of a proton = radius of a neutron = 1*10^-15 m
size of an atom: 1*10^-10 m
size of a molecule: From (1*10^-10) - (1*10^-6) m
and just rattafy the values of either the wavelengths or frequencies, cause you can calculate the other quantity if you know any one of them (since speed of light is already known)
Oh and also the questions that require you to calculate the mass of a nucleus, we multiply unified atomic mass constant with the number of the nucleons.
well, if you already know this, I just wanted to share this cause I used to multiply the atomic number with the rest mass of a proton and the number of neutrons with the unified atomic mass constant and then add the both since I thought protons and neutrons have their own different masses. But for a nucleus, we assume the Nucleons (protons and neutrons both) have the same mass of 1.66*10-27.

 

[Jiyad Ahsan]

yeah i think that is y we are getting halwa papers this far bcz of the no holz in btween situation.. ooh stats is gonna make us feel like a chimp in the CAR?.... wat u said X|

you do understand a halwa paper means a higher threshold...

 

[Beaconite007]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w10_qp_22.pdf
Does anybody know a way of finding the area under a curve without having to count the blocks?
Example: Q4 (b)

 

[daredevil]

Dont forget these (they're the ones that I came across while solving the past papers and are not mentioned in the book ) :
mass of a nucleus: 1*10^-25 kg
radius of a nucleus: From 1*10^-15 - (1*10^-14) m
radius of a proton = radius of a neutron = 1*10^-15 m
size of an atom: 1*10^-10 m
size of a molecule: From (1*10^-10) - (1*10^-6) m
and just rattafy the values of either the wavelengths or frequencies, cause you can calculate the other quantity if you know any one of them (since speed of light is already known)
Oh and also the questions that require you to calculate the mass of a nucleus, we multiply unified atomic mass constant with the number of the nucleons.
well, if you already know this, I just wanted to share this cause I used to multiply the atomic number with the rest mass of a proton and the number of neutrons with the unified atomic mass constant and then add the both since I thought protons and neutrons have their own different masses. But for a nucleus, we assume the Nucleons (protons and neutrons both) have the same mass of 1.66*10-27.

jalisjdfiajflsf.... waT??
wat wsa that about nucleus and stuff... can you post a question like that and also eplain it a bit puhllleeezzz!!

 

[asd]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w10_qp_22.pdf
Does anybody know a way of finding the area under a curve without having to count the blocks?
Example: Q4 (b)

Yeah I have the same problem, but what I always do is consider the curve as a straight line which doesnt always give the exact answer.

 

[A star]

you do understand a halwa paper means a higher threshold...

hmmmmm well the highest theyy can give is 43

 

[daredevil]

you do understand a halwa paper means a higher threshold...

yeahh.... :/

 

[ZainH]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w10_qp_22.pdf
Does anybody know a way of finding the area under a curve without having to count the blocks?
Example: Q4 (b)

You draw a tangent to the curve so you have a triangle and find the area of that.

 

[Beaconite007]

Yeah I have the same problem, but what I always do is consider the curve as a straight line which doesnt always give the exact answer.

True, might as well do that and add/subtract a random number from it.
We only have 1 hour for this paper, can't expect us to stay on one question's one part for 5 mins :s
And besides, my eyes give away and I forgot which blocks I counted and which ones I left out.
Not to mention some are half, a quarter or 3 quarters >_>

 

[Beaconite007]

You draw a tangent to the curve so you have a triangle and find the area of that.

But wouldn't that give a slightly greater/lesser value than the actual?

 

[Jiyad Ahsan]

jalisjdfiajflsf.... waT??
wat wsa that about nucleus and stuff... can you post a question like that and also eplain it a bit puhllleeezzz!!

umm the mass of a neutron or a proton is given(something around 1.67x10^-27 kg)... so if they ask you to find the mass of lets say of carbon you know there are 6 protons and 6 neutrons so just add em.. like (6 x mass of proton) + (6 x mass of neutron)

 

[asd]

jalisjdfiajflsf.... waT??
wat wsa that about nucleus and stuff... can you post a question like that and also eplain it a bit puhllleeezzz!!

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_s10_qp_21.pdf
q7

 

[ZainH]

But wouldn't that give a slightly greater/lesser value than the actual?

Yeah it would, but theres usually a range of values when it comes to finding the area under a curve.
If you're feeling unsure about the area of the triangle just make the approximation sign and write your value OR add/subtract a reasonable amount from it.

 

[asd]

umm the mass of a neutron or a proton is given(something around 1.67x10^-27)... so if they ask you to find the mass of lets say of carbon you know there are 6 protons and 6 neutrons so just add em.. like (6 x mass of proton) + (6 x mass of neutron)

Thats exactly what I told you NOT to do.
I checked the ms, they just use the UNIFIED ATOMIC MASS CONSTANT for both. so if you have like 12 nucleons, regardless of whatever the number of protons is, you multiply 12 by 1.66*10^-27

 

[lubna1232]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w12_qp_23.pdf

guyss Q1 e pleaseee ? and 2a part ii as well. i dont get them :'(

 

[asd]

Yeah it would, but theres usually a range of values when it comes to finding the area under a curve.
If you're feeling unsure about the area of the triangle just make the approximation sign and write your value OR add/subtract a reasonable amount from it.

have you tried the method? like does it give the value anywhere close to the answer?
cause I dont think it does

 

[goodluckayesha]

Thank you !! What abt my other question abt the wave...do u happen to know it ?
Thx again

umm I noe the answer but dunno y is it the answer sorry if anything else do ask id b happy to help if I can

 

[ZainH]

have you tried the method? like does it give the value anywhere close to the answer?
cause I dont think it does

It does, I didn't make it up my teacher told me.