Physics P5, HELP!

[D-chris91]

Hi, this is really bugging me. I am a prepare-by-self-with-God's-help student and I don't have anyone else to ask. How does one calculate the absolute error in log of a quantity. For example, current, I= 2.6 +/- 0.1A. What is log I including absolute error?
Also, can anyone list safety precautions for Paper 5?

[falafail]

the error in a logarithm is the difference between the max. value and the "best" value
for example, if you have to find log x, where x = y +/- z
you find the max. value, which is log (y + z)
and the best value, which is log y
the difference between these two values is the error.

[ny2ko]

I usually take the difference between the max value and min value then divide by 2. that seems to work

[D-chris91]

Also, can anyone please teach me how to find areas under curve, in case of such a question arising in Paper 2?

[falafail]

Also, can anyone please teach me how to find areas under curve, in case of such a question arising in Paper 2?

i don't remember ever having to do that in paper 2?

but here http://www.mathsrevision.net/alevel/pages.php?page=2

[aorta]

Also, can anyone please teach me how to find areas under curve, in case of such a question arising in Paper 2?

In paper 4, we count the squares and the convert them to the appropriate units. So, I don't think that you really need to integrate.

Anyways, you don't have to find the area of curves but the area of a triangle...

[aorta]

the error in a logarithm is the difference between the max. value and the "best" value
for example, if you have to find log x, where x = y +/- z
you find the max. value, which is log (y + z)
and the best value, which is log y
the difference between these two values is the error.

Can you please explain this?! I don't get it..

Lets say we have: 3.5 ± 1.0 , and we want to find the log and absolute error.

The log would be 0.544 but what would be the absolute error?! If I use the above equation you gave, I'll get 0.012 but the MS answer is 0.017!!

How do you do this?

[falafail]

Can you please explain this?! I don't get it..

Lets say we have: 3.5 ± 1.0 , and we want to find the log and absolute error.

The log would be 0.544 but what would be the absolute error?! If I use the above equation you gave, I'll get 0.012 but the MS answer is 0.017!!

How do you do this?

 
i don't know i got 0.12 :/

[Twinkle Charms]

i don't know i got 0.12 :/

yep me too got 0.12, either ways mentioned here, ull get 0.12.

[aorta]

i don't know i got 0.12 :/

   It's May/June 2009 By the way.

[falafail]

  It's May/June 2009 By the way.

it is 0.012. 0.016 is the FIRST value, DECREASING TO 0.006.
0.012 is in the range so i'm prettty sure it's right..

[Twinkle Charms]

  It's May/June 2009 By the way.

there u go rong, u said error is 1.0, whereas its 0.1, and in the mark scheme tht is the range given for the first answer, that is the first error can be either 0.016 or 0.017.

[Twinkle Charms]

ok my doubt jun08 (paper attached)
how do we know which is the dependant and independant variable?? =\

[aorta]

it is 0.012. 0.016 is the FIRST value, DECREASING TO 0.006.
0.012 is in the range so i'm prettty sure it's right..

OMG!! THANK YOU!! It says OR ... lol OKayy thanks a looot

[falafail]

no problem

ok my doubt jun08 (paper attached)
how do we know which is the dependant and independant variable?? =\

are you going to sleep soon? i'm doing nov 09 atm. i'll do june 08 and help you when i'm done if you're still here and if no one else has