P.H.Y.S.I.C.S P2 D.O.U.B.T.S CIE

[halosh92]

nov 2007
Q4d

nov 2005
Q4ai, ii

in the ms its 42+/- 4 cm/s
dont we have to change it to meters ?
and where did they get the +/-4  from
similarly for the second part, where did they get that uncertainity from?

[Meticulous]

nov 2007
Q4d

It's exactly like the steel and concrete combination. Why is concrete stronger in compression and weaker in tension? Because in tension the extensions of top and bottom layers vary, and so it shatters. The opposite goes for steel.

The exact same case here. However, the difference in extensions in the thicker rod is greater, and so it breaks easier. i.e require less bending.

[Meticulous]

nov 2005
Q4ai, ii

in the ms its 42+/- 4 cm/s
dont we have to change it to meters ?
and where did they get the +/-4  from
similarly for the second part, where did they get that uncertainity from?

No you don't have to change them to meters. Actually, it's preferable to keep them as it's given to you! It's given to you in cm, then keep it in cm. BUT, if you change it to meters, it would still be right. However, the probability of making an error is increased as now you have to divide by a 100 (you could type 10 in your calculator)

And, for the second part, it's not uncertainty. It's just the range of ACCEPTABLE values by students, as your answer varies from another's. It's not for you, it's for the examiners. As long as your answer lies in the range, you're safe.

[Meticulous]

Was I clear ?

[halosh92]

No you don't have to change them to meters. Actually, it's preferable to keep them as it's given to you! It's given to you in cm, then keep it in cm. BUT, if you change it to meters, it would still be right. However, the probability of making an error is increased as now you have to divide by a 100 (you could type 10 in your calculator)

And, for the second part, it's not uncertainty. It's just the range of ACCEPTABLE values by students, as your answer varies from another's. It's not for you, it's for the examiners. As long as your answer lies in the range, you're safe.

so basically the +/-4 is not the uncertainity.
and for this question the final answer MUST be in m.
so i have to divide 42 by 100 ..correct?
THX A BUNCH 

[Meticulous]

so basically the +/-4 is not the uncertainity.
and for this question the final answer MUST be in m.
so i have to divide 42 by 100 ..correct?
THX A BUNCH 

Yes. +/- 4 is not part of the uncertainty. They will ask for it DIRECTLY in the exam.

And NO! You got me totally wrong! LOL I said it's preferable to keep it in CM, as it is given to you in the question, so ther's a less chance of making errors!

Was I clear, again?

And don't thank me, it's my job

[halosh92]

Yes. +/- 4 is not part of the uncertainty. They will ask for it DIRECTLY in the exam.

And NO! You got me totally wrong! LOL I said it's preferable to keep it in CM, as it is given to you in the question, so ther's a less chance of making errors!

Was I clear, again?

And don't thank me, it's my job

hhahah i got u yep....but if u look at the question in the space where we have to write the answer the unit theyve given is meters xD
hahah and dude i cant help NOT thanking u

[Meticulous]

hhahah i got u yep....but if u look at the question in the space where we have to write the answer the unit theyve given is meters xD
hahah and dude i cant help NOT thanking u

Oooppss.. my bad then yes..your answer should be in meters if it's written to you.

And I know you cannt help thanking me LOL JK..its alright

[halosh92]

 
june 2005
p2
Q6bi
could someone draw and explain why the directions are in such a manner???
thx

[nid404]

june 2005
p2
Q6bi
could someone draw and explain why the directions are in such a manner???
thx

I know that the +ve charge will experience a force towards the right. That is because electric field is from +ve plate to the negative plate. +ve charge will experience a pull towards the negative plate. The -ve charge just the opp.

The ms says correct directions with line of action of arrows passing through charges...Now I wonder if we have to show the force that the charge experiences due to the other. (force that once charge has on the other) 

[halosh92]

I know that the +ve charge will experience a force towards the right. That is because electric field is from +ve plate to the negative plate. +ve charge will experience a pull towards the negative plate. The -ve charge just the opp.

The ms says correct directions with line of action of arrows passing through charges...Now I wonder if we have to show the force that the charge experiences due to the other. (force that once charge has on the other) 

ahh u c the next questions are about couples, so i guess its just these 2 forces, maybe we just have to extend the lines?

[sizbeauty]

can u guyz recommend me a gud buk for physics?which is according to the syllabus and has all required formulas n definitionz...plz help me!!!!!

[halosh92]

june 2004 p2
Q4c

[Meticulous]

Please halosh, post the q paper.

[halosh92]

Please halosh, post the q paper.

there u go