# Physics P5 in 5 minutes !!!

#### bineetojha

here's a revision note for 9702 physics paper
Question 1:
first be able to reduce the equation in the simplest form ..i.e y=mX=c ..and recognize the gradient
calculate the data in 3 s.f(generally done) or to one s.f more or equal to the s.f of the raw data
in case of logarithmic calculations, the number of d.p is the number of s.f ..hence for a raw data of 3 s.f the log should be calculated to 3 or 4 d.p
to calculate absolute uncertainty the most accepted method is to calculate the maximum difference and divide by 2 ..sf of uncertainty is usually ignored in the mark scheme but stick to 1 or 2 s.f
plot all the six points,a small encircled dot is acceptable use sharp pencil to plot , and draw the error bars. all to nearest half square on the grid.
(u can also analyze from the graph as how much s.f to use..as the graphs interval's points's tenth division place is to be plotted )
the gradient should be calculated by drawing a triangle and mentioning the points of the vertices in the best-fit line ..the hypotenuse should be greater than halt the length of the best-fit line.
working should be shown clearly
and the worst-fit line is drawn by joining the top of the topmost point's error bar and the bottom of the bottommost error bar..and the line should touch every error bar.
both line should be clearly LABELLED ,and the gradient of worst-fit is calculated in similar way to best-fit ..calculate it on the blank page at the end..and just show the gradient value in working area while calculating the uncertainty in gradient..
the error in gradient is gradient of best fit - gradient of worst fit ,or 1/2 * (steepest line's gradient - shallowest line's gradient)
all calculation to 3 s.f
and for calculations , which is usually related to the calculated gradient, take care of units, power of tens and to calculate the percentage uncertainty work out the value with the gradient and again with the error+the gradient and work out the difference which is the absolute uncertainty , hence calculate the percentage uncertainty .(working is only credited here and calculations are not checked)
Question 2:
state the basic statement, it is awarded 1 mark..such as change pressure and measure power..and repeat(o/n 05)
Draw a diagram with all the equipment you might use during the experimentation of this plan..a basic, well labelled diagram could score many marks; even if the explanation is weak.
identify the control variable
make sure you know the working of some equipments as:
collimator,sonometer, strobe, bourdon gauge, joule meter,thermometers,light-spot galvanometer needle valve, vacuum grease , lightgate, smart pulley ,balance,newton meter,ticker tape data-loggers , optical bench, set squares etc.. don't panic of you don't but u should know what equipment to use to measure something.
make sure u understand the question and collect all the method marks by suggesting means of measuring the quantities u might measure during the experiment.
there are 5 method marks to be scored.
now beware of safety measures. like earmuffs eardrums, goggles , safety screens . sand bucket for falling masses..etc
now be able to point some additional details they are worth 4 marks.
these can also be awarded on a detailed diagram..
suggest the possible ranges of devices, suggest some ways of sophisticating the experiment..but donot make vague references and do not forget why are u performing this experiment .
Best of luck . :Yahoo!: bineetojha

#### Sully17

Thanks a lot i hope this helps ;D

#### bineetojha

Thank you !! and any further discussions and suggestions are welcomed !!

• MEGUSTA_xD

#### fatema

hey, bineetojha
can u please help me by telling me how these instruments work: collimator,sonometer, strobe, bourdon gauge, joule meter,thermometers,light-spot galvanometer needle valve, vacuum grease , lightgate, smart pulley ,balance,newton meter,ticker tape data-loggers , optical bench, set squares and if there are any other instruments that we need to know please.

Thanks alott

• gary221 and sumaiyarox:)

#### yewtzeee

Do u have any diagram for q1 of paper 5 physics..

#### MukeshG93

Very nice compilation. I like it. Also, don't forget the elementary instruments!!!

• gary221

#### sara1991

• haroon740

#### bineetojha

..how was the exam guyz..???

#### mr_perfect

i did bad in my physics paper 42 too . but not that bad. will proly get around 53 or sumthin. i got only one xam left now which is Physics PAper 52 @ 30th May 2012. if i score like 21 out of 30 in it . can i get an A in physix ??? i got A(82%) in my AS level . plz sum1 lemme know if i can score an overall A in Physix . tnx . #### hassam

wellll can some one tell me how the uniform magnetic field would be produced, measured and changed

#### aatifdesai

here's a revision note for 9702 physics paper
Question 1:
first be able to reduce the equation in the simplest form ..i.e y=mX=c ..and recognize the gradient
calculate the data in 3 s.f(generally done) or to one s.f more or equal to the s.f of the raw data
in case of logarithmic calculations, the number of d.p is the number of s.f ..hence for a raw data of 3 s.f the log should be calculated to 3 or 4 d.p
to calculate absolute uncertainty the most accepted method is to calculate the maximum difference and divide by 2 ..sf of uncertainty is usually ignored in the mark scheme but stick to 1 or 2 s.f

as u said to calculate the maximum difference and divide by 2
BUT CALCULAT THE MAXIMUM DIFFERENCE FOR WHAT.....?

PLEASE HELP FAST.

#### Albert Einstein

does the line of worst fit need to pass through all error bars ??

#### Ashayn

does the line of worst fit need to pass through all error bars ??
Yes... definitely

#### Saloon

Hey could someone tell me to find the absolute error of a log eg. 1.2+/- 0.1 can i do it like this [(0.1)/(1.2)] * [log(1.2)]? Or is this wrong?

And if if there is no log it would just be.... (0.1/1.2) * 100 right?

Its from october november 2007

#### Taci12

Hey could someone tell me to find the absolute error of a log eg. 1.2+/- 0.1 can i do it like this [(0.1)/(1.2)] * [log(1.2)]? Or is this wrong?

And if if there is no log it would just be.... (0.1/1.2) * 100 right?

Its from october november 2007
If a function such as log or ln is used to calculate the values, then for e.g value is 6.0 +/- 0.5, to find error:

absolute error = log (6.0+o.5) - log 6.0

• Millatina and Saloon

#### Saloon

If a function such as log or ln is used to calculate the values, then for e.g value is 6.0 +/- 0.5, to find error:

absolute error = log (6.0+o.5) - log 6.0
Sweet thanks, i was reading other threads too, thats the same as doing this:
(Log(6.5)-log(5.5))/2 and also log(6.5/6.0) right? Even though the answers are slightly different?

Oh and also is absolute error the same as absolute uncertainty?

#### Taci12

Sweet thanks, i was reading other threads too, thats the same as doing this:
(Log(6.5)-log(5.5))/2 and also log(6.5/6.0) right? Even though the answers are slightly different?

Oh and also is absolute error the same as absolute uncertainty?
Yes, you can do either of these 3 to get the answer. However I prefer the way I showed you, more simple and less chance of making a mistake while typing in values on the calculator.

Errors and uncertainties are not quite the same, the difference is that uncertainty is a quantity that is associated with an estimate whose true value is not known. Error is a quantity that is associated with an estimate whose true/accepted value is known.

But for our A-level papers, they tend to mean the same thing • Saloon

#### Saloon

Yes, you can do either of these 3 to get the answer. However I prefer the way I showed you, more simple and less chance of making a mistake while typing in values on the calculator.

Errors and uncertainties are not quite the same, the difference is that uncertainty is a quantity that is associated with an estimate whose true value is not known. Error is a quantity that is associated with an estimate whose true/accepted value is known.

But for our A-level papers, they tend to mean the same thing Okie thanks sooo much was trying to figure this out... Just one last thing though if they tell us to square a value but not log it the, for example: 2.1+-0.1.
You would first square it put the answer down and for error how would you do it?
This is a questions from october november 2008 paper 5 question number 2b
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w08_qp_5.pdf

Thank you for your help #### Taci12

Okie thanks sooo much was trying to figure this out... Just one last thing though if they tell us to square a value but not log it the, for example: 2.1+-0.1.
You would first square it put the answer down and for error how would you do it?
This is a questions from october november 2008 paper 5 question number 2b
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w08_qp_5.pdf

Thank you for your help If you have to square the value, you must add the fractional or percentage uncertainties to get the final uncertainty.
e.g if x=2.1 +/- 0.1
for the answer: x^2=2.1^2=4.41
fractional error = 2 x (0.1/2.1)
absolute error= fractional error x 4.41 = 0.42

final answer : x^2 = 4.41 +/- 0.42 units

Cambridge accepts the above answer, it also accepts if you give the error to one decimal place : 4.4 +/- 0.4. So that's upto you.

My pleasure! Feel free to ask if you have other problems. All the best for exams • sumaiyarox:) and Saloon

#### Saloon

If you have to square the value, you must add the fractional or percentage uncertainties to get the final uncertainty.
e.g if x=2.1 +/- 0.1
for the answer: x^2=2.1^2=4.41
fractional error = 2 x (0.1/2.1)
absolute error= fractional error x 4.41 = 0.42

final answer : x^2 = 4.41 +/- 0.42 units

Cambridge accepts the above answer, it also accepts if you give the error to one decimal place : 4.4 +/- 0.4. So that's upto you.

My pleasure! Feel free to ask if you have other problems. All the best for exams Thank you i got it now Are you also writing?

• sumaiyarox:)