HOW WAS PHYSICS PAPER 2 AS!!!!!!!!!!!

[Knight]

n for the steel question, they asked us 2 name 2 other quantities..i wrote area at first n then changed to radius/diameter (not sure which 1)...coz it was stated there as quantity measured..n area cnt really be measured rite..any opinion guys??

i wrote
1: original length using meter rule
2: diameter using micrometer screw gauge then calculate area by using the formula.......

 

[rabiafarooq101]

nope. there is work done against frictional force

The gain in potential energy was in fact equal to the output power because output power = Total energy-work done against friction. So the gain in potential energy was the effective work output once you subtracted the frictional force. The kinetic energy was obviously constant because the log was moving with constant velocity.

 

[rabiafarooq101]

No it was not because some work is also done against friction. (This should be sufficient for 2 marks) So output power would be rather the sum of gain in potential energy per unit time and work done against friction per unit time.

OUTPUT POWER is the effective power once you subtract the work done against friction. Have you ever calculated efficiency of a system? If you have then you might remember that output power is the effective power.

 

[rabiafarooq101]

Current falls
Pd falls

Current increases as the total resistance of the circuit was decreasing. V=IR. So I is inversely proportional to R. R decreases, I increases.

 

[ryabenz]

i wrote
1: original length using meter rule
2: diameter using micrometer screw gauge then calculate area by using the formula.......

i wrote tht too

 

[AppleGreen]

OUTPUT POWER is the effective power once you subtract the work done against friction. Have you ever calculated efficiency of a system? If you have then you might remember that output power is the effective power.

Please read up some books before u say this.
Efficiency= EFFECTIVE power output/ energy input.
Output power refers to effective power + power loss.

 

[AppleGreen]

The gain in potential energy was in fact equal to the output power because output power = Total energy-work done against friction. So the gain in potential energy was the effective work output once you subtracted the frictional force. The kinetic energy was obviously constant because the log was moving with constant velocity.

you don't understand the ques dudette

 

[Mattman]

Current falls
Pd falls

sry i meant current increases

 

[WhereAmazingHappens]

It was in equilibrium, because it was moving at constant velocity, no resultant force acting on it and no resultant moment either.

are u sure about that? i wrote the same thing as you but when u apply
F=ma
since a=0
F-850=0
F=850
(850 is resistive force)
So there is a resultant force on it

 

[WhereAmazingHappens]

n for the steel question, they asked us 2 name 2 other quantities..i wrote area at first n then changed to radius/diameter (not sure which 1)...coz it was stated there as quantity measured..n area cnt really be measured rite..any opinion guys??

nah area and radius are both correct because u need to measure the radius to get the area so its kinda like measuring the area so both r correct it think

 

[AppleGreen]

are u sure about that? i wrote the same thing as you but when u apply
F=ma
since a=0
F-850=0
F=850
(850 is resistive force)
So there is a resultant force on it

Resultant force means the sum of diff forces in a system. T and F cancel out each other so resultant= 0

 

[WhereAmazingHappens]

Resultant force means the sum of diff forces in a system. T and F cancel out each other so resultant= 0

ah ok thanx

 

[good man12]

I know, but most of my friends tell me that since we are taking inverse of V/t, the power will come infront and it will become negative :S..
I hope you and I are right. My uncertainty value was 8.9 X 10^-5

also , my value of C came 1.035X10^-3
in the next question after uncertainty, the significant figure one,
I wrote it as : 1.04 X10^-3 + or - .089 X 10-3

is it right? some of them are telling I have to round up .089 to .09 :S.. what are your remakrs about that?


BTW, if my uncertainty value is wrong, will they allow ecf for the appropriate significant figure question ?

ANYONE LOOKING AT THIS, WOULD BE NICE IF YOU ANSWERED .. thanks.

dont worry, its fine, but u should have rounded to 3 sig fig as in all the data there were 3... Any body very sound in math would know that in place of w/t you could substitute it in to X and solve the eqation....now no need for inverse.....mine was 0.00104+-0.00009 ( which is confirmed correct)

 

[good man12]

Oh, and also, for the very last part of question two where you had to state and explain the over all change in energy, what did you write?
only about the conversion of GE to KE at the plate and then again about the conversion of KE to GE at B?

well i wrote that the change in gpe is grater then change in KE which suggests that some energy is lost during the balls collision with the ground...

 

[good man12]

OUTPUT POWER is the effective power once you subtract the work done against friction. Have you ever calculated efficiency of a system? If you have then you might remember that output power is the effective power.

total output power is just work done/time taken....not useful work done/time taken.............i say my car has a 20Kilo Watt powered engine, in order to calculate top speed i have to subtract power against resistence first.......it isnt included as you assume...any how..gain in pe was less as the motor does work against resistive forces too.

 

[good man12]

dude it was T=1517

T was :
1568 which i wrote as 1570.........

 

[AdeelRox]

T was :
1568 which i wrote as 1570.........

yea nw i remember it was 1567.something i also rounded it off to 1570N

 

[daniyal007]

in phy paper i wrote that micro meter screw guage will be used to calculate cross-sectional are rather than dia will be measured by micro meter and then area???? will i be penalised???

 

[applepie1996]

something like 1567 or 1576 some thing like that for T

i got sumthin lyk dat 2

 

[fathimaash]

i read the posts earlier n they said to get an A for the oct/now 2011 paper was just 30/60..is it so??

yes u cant evn imagine ryt i hope r GT is also low