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Physics: Post your doubts here!

Asad Moosvi

Asad Moosvi

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kitkat <3 :p said:
for Y=92 -57
for Z =235- 148 - 3 cux 3 neutrons are there

well not sure about the ii) part
when a reaction occurs then energy is realease and due to release of energy mass can be lost too so thats y the mass is nt equal :/
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But the mass is 236 on both sides. I'm so confused.
 
A

_Ahmad

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Asad Moosvi said:
COME ON GUYS PLEASE HELPPPPPPP. Q 7 LAST PART FROM http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s13_qp_23.pdf

PLEASE PLEASE PLEASE
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We can answer this by thinking about the energy which is carried away by the particles (alpha or beta) and electromagnetic radiation (gamma) produced in the decay.Albert Einstein realised that we can think of energy as having mass. So if the mass of the nucleus decreases we must look around and find the energy which is carrying away this mass.The greater the apparent loss in mass the greater the amount of energy which is escaping.
To sum up we talk about "mass-energy" . In any closed system the total amount of mass-energy is conserved. If the mass goes down energy goes up and vice versa, but the total is constant
 
Asad Moosvi

Asad Moosvi

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_Ahmad said:
We can answer this by thinking about the energy which is carried away by the particles (alpha or beta) and electromagnetic radiation (gamma) produced in the decay.Albert Einstein realised that we can think of energy as having mass. So if the mass of the nucleus decreases we must look around and find the energy which is carrying away this mass.The greater the apparent loss in mass the greater the amount of energy which is escaping.
To sum up we talk about "mass-energy" . In any closed system the total amount of mass-energy is conserved. If the mass goes down energy goes up and vice versa, but the total is constant
Click to expand...

You are quoting this from the physics as level course book. I don't understand why the question is saying the sum of the masses is not equal when if you compare both sides, the masses seem to be equal to me.
 
K

kitkat <3 :P

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Asad Moosvi said:
You are quoting this from the physics as level course book. I don't understand why the question is saying the sum of the masses is not equal when if you compare both sides, the masses seem to be equal to me.
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look what i think is u are mistaking the nucleon number with the mass :/ i can be wrong mass is something different when a particle undergoes a radioactive reaction it loses energy cuz of the radiations involved and thats y mass is lost......i can be wrong though :oops:
 
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_Ahmad

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Asad Moosvi said:
You are quoting this from the physics as level course book. I don't understand why the question is saying the sum of the masses is not equal when if you compare both sides, the masses seem to be equal to me.
Click to expand...

neither mass nor energy is conserved separately, but that they could be traded one for the other and only the total "mass-energy" is conserved
 
Suchal Riaz

Suchal Riaz

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kitkat <3 :p said:
Suchal Riaz
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we don't talk about mass in radioactive decays because the mass of a particle is different when they are moving as they move at very high speed. we talk about their energies. E=MC² and their kinetic energy. the energy can be in form of mass or in form of kinetic energy. in A level write 'mass-energy' is conserved.
although nucleon number are number of nucleons not the mass. means number of proton+neutrons are conserved.
 
princeali97

princeali97

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Asad Moosvi said:
Can someone please explain Q5 part b to me from the following paper? http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s13_qp_23.pdf
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I can explain you the last part i.e (ii) cuz other parts seem easy.
Wave traveling from S to X moves a distance of 5m.(simple pythagoras theorem i.e (4^2+3^2)^0.5
Wave traveling through SPX moves a distance of 7m.
So whats the path difference? 7-5 = 2m
Since for constructive interference path difference is n lamba, there will be maxima formed at X.
 
K

kitkat <3 :P

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Suchal Riaz said:
we don't talk about mass in radioactive decays because the mass of a particle is different when they are moving as they move at very high speed. we talk about their energies. E=MC² and their kinetic energy. the energy can be in form of mass or in form of kinetic energy. in A level write 'mass-energy' is conserved.
although nucleon number are number of nucleons not the mass. means number of proton+neutrons are conserved.
Click to expand...

thank u ^_^
 
princeali97

princeali97

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Asad Moosvi said:
But the mass is 236 on both sides. I'm so confused.
Click to expand...
Asad bhai no need to be confused.Theres a simple concept.In a radioactive decay,both nucleon and proton number are conserved.But the total mass of the particles after decay is less than that before the decay which is because of some loss of energy in the form of electromagnetic radiation.
 
K

kitkat <3 :P

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K

kitkat <3 :P

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