PHYA1 - Physics Unit 1 Exam - 24th May 2011

the question where they asked for the characteristics of kaon which make them strange,
i see answers like "they have strange quark" but is it really a characteristic?
i put "they are created through strong interaction but decay through weak interaction, and that they are relatively long-lived"
i'm really unsure about this one though..

while thats a characteristic its not a unique one, non strange particles are also created through the strong and decay through the weak, baryons have this characteristic and a lot of baryons are not strange.
I put that strange particles include pie mesons in the decay and i agree, having a strange quark is not really a characteristic.

Reply 181

hwalker37

Original post by Limitless

I wrote about the creating via strong interaction and decaying via weak. but it seemed to long at it said ONE characteristic so I changed it to strange quark.

You forget AQA only mark positively :wink:

Even if it explicitly says ONE writing more does no harm. Last year a question was 'Name TWO properties that are conserved in this collision.' One of my friends listed about 8 (including some ridiculous ones i.e temperature) and got the two marks :confused:

Beggars belief :rolleyes:

anyone? .........

Original post by Rocketeeer

ohhh.. yeah i put down 2 regardless, too insecure..
but is "having a strange quark" a characteristic?

I thought AQA are really picky on this thought of thing. I've been told if ask for one characteristic and you right two only the first one gets mark.

Reply 184

Rocketeeer

Original post by rub em out

while thats a characteristic its not a unique one, non strange particles are also created through the strong and decay through the weak, baryons have this characteristic and a lot of baryons are not strange.
I put that strange particles include pie mesons in the decay and i agree, having a strange quark is not really a characteristic.

yeah that's why im not sure, this characteristic is not an exclusive one
what about "relatively long-lived" i remember my physics teacher saying sth about that
although the book actually referred to them as "short-lived" particles.. :frown:

The book said "these properties of K mesons led to them being called strange particles"

Reply 185

A level Az

16

If you're asked to list one thing, and you list either:

one right thing and one wrong thing
two right things and one wrong thing
one right thing and 2+ wrong things

Then don't see how they could give you the mark. However if you list two right things then you probably would.

And for that question I really believe the answer was related to the strange quark because the part before asked about the quarks in protons and neutrons, and parts of the same question are often related in some way.

Reply 186

Naum

For the characteristic of the strange particle I put: They have the property of strangeness associate with them.
Is that fine?

Reply 187

Limitless

Original post by hwalker37

You forget AQA only mark positively :wink:

Even if it explicitly says ONE writing more does no harm. Last year a question was 'Name TWO properties that are conserved in this collision.' One of my friends listed about 8 (including some ridiculous ones i.e temperature) and got the two marks :confused:

Beggars belief :rolleyes:

AQA mark inconsistently. Some are really generous markers others are just harsh. Question worded in a really stupid manner. I hate AQA.

Reply 188

maths134

13

Well I liked it, annoyed no photoelectric effect but the grade boundaries AQA give are always laughable (62 for 120ums !?). Is anyone going to post a mark scheme of some sort ? only question im aware I got wrong was the 'what interaction is not possible' is because Im an idiot =/ and cant read a data sheet. The 'tricky' or 'discrimination' questions in the paper will probably be the 'where does the electron come from' (actually got this right) the vague one on strangeness.
What do people think the marks in the 6 mark question will be for ? I would say -
- bombarding electrons 'excite' atomic electrons in vapour
- They raise to 'higher discrete energy levels'
- The 'de-excite' and cascade down the levels.
- Each transition has an exact value E=E1-E2 (or whatever it was)
- Each transition emits a photon of exact energy
- Each photon corrosponds to an exact freqency E=hf
- Each freqenecy corrosponds to a colour hence we get discrete lines.

Anything else ? lol did we need to 'prove' that 3 was r, because I did this then plugged it in to get 5, was it needed to show it was 3 in the first place ?

Reply 189

Rocketeeer

Actually the book also said sth about "They were called strange particles after investigations showed that the V tracks decay into pie mesons only, or into pie mesons and protons"
i think the right answer is "they always directly decay into pie mesons"

Reply 190

hwalker37

Original post by A level Az

If you're asked to list one thing, and you list either:

one right thing and one wrong thing
two right things and one wrong thing
one right thing and 2+ wrong things

Then don't see how they could give you the mark. However if you list two right things then you probably would.

And for that question I really believe the answer was related to the strange quark because the part before asked about the quarks in protons and neutrons, and parts of the same question are often related in some way.

1 right thing is enough :smile:

The only exception I've seen is if something directly contradicts the right answer. E.g 'Give one characteristic of an electron' Basically if you say an electron is both positively and negatively charged you would be wrong, however, if you say it is negatively charged and has an unusual attraction to chickens you would be correct and get the mark :biggrin:

Reply 191

Rocketeeer

Original post by Limitless

I thought AQA are really picky on this thought of thing. I've been told if ask for one characteristic and you right two only the first one gets mark.

then its the "relatively long-lived" one :s-smilie:

Reply 192

Limitless

Original post by Rocketeeer

then its the "relatively long-lived" one :s-smilie:

I'm confused. :s-smilie:

. I hate it can't wait to drop it next year.

Reply 193

bubblebuddy

What was question 3? I can't remember it and I'm beginning to think I missed a question D:

Reply 194

Limitless

Original post by bubblebuddy

What was question 3? I can't remember it and I'm beginning to think I missed a question D:

Dunno. I've got the attention span of a relatively short lived antiparticle.

Reply 195

biologyunit1may16

i thought proton is most stable hadron :s-smilie:

i got 4v, not 2 for the last 1, would i lose 1 mark?

Reply 196

ahalis94

Original post by bubblebuddy

What was question 3? I can't remember it and I'm beginning to think I missed a question D:

it was the one with the feynman diagram and you had to state what how the atom decayed into argon etc....

Reply 197

Limitless

Original post by hwalker37

1 right thing is enough :smile:

The only exception I've seen is if something directly contradicts the right answer. E.g 'Give one characteristic of an electron' Basically if you say an electron is both positively and negatively charged you would be wrong, however, if you say it is negatively charged and has an unusual attraction to chickens you would be correct and get the mark :biggrin:

Electron + Chicken = Chicken capture. Duhh.