A levels Physics. Help please! Thanks!

OHSheet SG

ok guys, im just not really sure on several physics concepts here.

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ok, these are what i understand and have been studying,

For a Beta decay... it results in the formation of electrons and anti-neutrino. It was noted that the KE of electrons given out during Beta decay fell, as the no. of electrons fell, in a somewhat EXPONENTIAL graph ( Therefore causing a missing amt of energy in the calculations) .

Therefore, Pauli proposed the formation of anti-neutrino during a beta decay, as according to the law of conservation of energy- as this missing energy had be carried off somewhere by something.

The properties of an anti-neutrino:

-zero mass rest

-travels at the speed of light

-very penetrative..

***** qn im not sure abt here.. if it has 0 mass rest, then how can it be possible for it to reach the speed of light?

I mean like... the equation E=mc^2, by rearranging, to reach (c) which is 3x10^8, c^2=E/m .. means that... you'd need at least SOME mass to reach (c), it cant be 0, as the properties stated. I really dont quite get it here how it works.

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*(note, this is a bogging question in my mind, about how the validity of the properties of the antineutrino- its not a question in any Alevels or whatsoever)

*****and yes... one more thing..

does anybody here have a great depth in understanding of Quarks?

As in those of Baryons(3 quarks), Mesons(2 quarks), leptons and hadrons, for sub-atomic particles?

like explain why for

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an up quark has charge of +2/3e, down quark =-1/3e

a Strange quark has charge of -1/3e, and a Charm quark has +2/3e.. Thanks looots!!

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:DDDDDD

Audioboxing SG

Precisely because it has zero rest mass it must travel at c to have a finite amount of energy. If this confounds you, it means you have not studied relativity with enough depth.

However, at the present time it is still unclear if the neutrino has zero rest mass or not, except that it has to be very small according to the most precise experiments.

As for quarks, your question will be better asked in more advanced forums than over here.

Istvan SG

Depending on who you ask, neutrinos either have a small and non-zero mass or are massless, and thus either travel very very close to c or at c. But generally it's agreed that they do have masses.

ideas in subatomic physics are pretty abstract. It's impossible to answer why " quarks have partial charges ". A close attempt would be to say that theoretical models have long predicted the existence of quarks (among other sub-atomic particles) and that through observation of hadrons, their existence have been "proven". It's impossible to observe quarks directly.

OHSheet SG

Hi! thanks guys for your replies.

But Istvan, im referring to antineutrinos here, not neutrinos. They're 2 different stuff. The antineutrino is an antiparticle of a neutrino. Where it differs in charge, but has the same mass.

Antineutrinos also have a different helicity as compared to neutrinos. Thanks. I was wondering about the validity of their properties.

Istvan SG

Hi! thanks guys for your replies.

But Istvan, im referring to antineutrinos here, not neutrinos. They're 2 different stuff. The antineutrino is an antiparticle of a neutrino. Where it differs in charge, but has the same mass.

Antineutrinos also have a different helicity as compared to neutrinos. Thanks. I was wondering about the validity of their properties.

Unless I have been sleeping through my physics classes, most particles and their associated anti-particles have symmetric properties. If the neutrino has mass, then the anti-neutrino also does. If the neutrino travels at c, so does its anti-particle.

I must admit that I am not yet familiar with concepts as helicity and spin. But for the purpose of discussion, neutrinos and anti-neutrinos have the same behaviour in relativistic mechanics.