AS Physics Practical - Paper 34

[stareaj]

Me too pleaseeeeee ...

Me tooooooo

 

[pakiboy]

What Will be the absolute error of the newton metre???????????

 

[saqib95]

Yes, I deleted my post for safety reasons and please also delete your above quoted post of mine inbox me I'll tell you the details.

Brother plz inbox me the details please.... asap

 

[samiaaaaaaaaaaaaahhh]

Brother plz inbox me the details please.... asap

inbox me too

 

[pakiboy]

Brother plz inbox me the details please.... asap

me 2

 

[Binod Shakya]

so its

I confirm this is absolutely right!

about heat and balancing the ruler
am i wrong or right??

 

[Talha Iqbal]

I

Yes, I deleted my post for safety reasons and please also delete your above quoted post of mine inbox me I'll tell you the details.

inbox me as well brother.

 

[Talha Iqbal]

yaar

Thanks so much for this! but i really understood nothing in the uncertainties part :/ could you please elaborate?

its really very easy. to calculate the uncertainty just divide the least count of your apparatus by 2. and to calculate the percentage uncertainty put the uncertainty as the numenator, ur calculated value as denominator and multiply by 100.

 

[saqib95]

Theres no question on heat...my physics teacher is a supervisor at a centre...question is on tubes in wgich we will have to add water and measure volume (thats a guess). The tubes are similar to those at the back of a syringe. And theres a vernier calliper. Most probably theyll ask us to find the volune flow rate of water. And theres a 200ml beaker too. More updates coming soon... And yeah he also said that the appratus would be new for all of us since this appartus has never been used before..

 

[Ahmed Khalel]

and to help u guys for tomorrows paper here are some tips.

Oscillations

* Perform 3 sets of measurements for each different oscillation, (you will get more marks if you do 2 sets of repeats).
* Measure at least 30 periods in total.
* Preferably make each measurement 20 periods long.
* Precaution: minimize oscillations in any other plane other than the one being observed
* Always write times to two d.p., never to the nearest second.
* Precaution: do small amplitude oscillations
* Precaution: say that you did several periods at once to minimize reaction time errors.
Moments

* Precaution: balance the ruler being used first.
* Use distances from the pivot of greater than 25 cm (250 mm).
* Weigh the unknown and known masses in your hands before using the ruler, and place the lighter mass as far from the pivot as possible.
* Measure distances from the pivot to the centre of mass of the object.
* All measurements should be to 1 mm accuracy.
* To make sure the rule is balanced, pull each end down. If it comes up again then the rule must have equal moments acting on it on either end.


Density Measurements

* When using a micrometer, one full rotation of the barrel is 0.5 mm (50 on the barrel scale).
* The micrometer reads to 0.01 mm accuracy.
* Vernier calipers can read to 0.05 mm accuracy. However, it is advisable to quote the figure to 0.1 mm accuracy, as this will give a larger uncertainty, which will make comparisons in later parts of the question easier.
* If measuring a very small dimension, measure several "thicknesses" of it. Remember to divide by the number of thicknesses after the measurement!
* Precaution: check the zero error on the micrometer and/or Vernier calipers. Wipe the jaws of the micrometer to remove grease.
* Give answers to 2 or 3 s.f. : it is meaningless to write, for example, "density is 7785.654 kg m-3"!
* Always take at least 3 readings for each measurement, and take an average.
* When measuring string diameters or foil thicknesses (or similar), use a minimum of 10 thicknesses.


Uncertainties

* % Uncertainty =
* When multiplying or dividing quantities, add their % uncertainties together.
* When adding or subtracting quantities, add their absolute errors together, then divide by the result of the addition/subtraction of the measurement, e.g. for , where , and , the absolute errors added = 0.102 mm. Therefore the % uncertainty is:
* If you have to calculate the error in, e.g. , the absolute error in d must be multiplied by pi and then added to the absolute error in x. The percentage uncertainty is this total error divided by the calculated and the result multiplied by 100.
* If a measurement is to be raised to a power, then multiply the % uncertainty in the measurement by the power to get the % uncertainty in the overall term.
* If two values, for say, a density are available, calculate the % difference between them. If a value is given by the examiner, then use this as the "correct" value, and calculate the % difference the following way: where x is your measured value, and c is the examiner's value. If you have obtained two values, then the expression changes: where x1 and x2 are your measured values, and is the median of the two, (not necessarily the mean!).
* Compare the % difference with your % uncertainty. Any relationship suggested, such as that the two densities should be equal, can be considered correct if your % difference is less than your % uncertainty. This will gain you marks!
* If your % uncertainties look small, check that you have multiplied by 100!


Graphs

* With any graph, a minimum of 6 to 8 points are needed, and you must have at least 4 points on a curve.
* When measuring the gradient of a graph, carry your tangent on to the sides of the graph paper, however big your graph. The triangle you use should be greater than 10 cm in length and height, although in some mark schemes 100 cm2 is fine.
* Your graph does not have to go through the origin. If the data does not indicate that it does so, do not force it to. Comment on the fact that there must have been a systematic error.
* When choosing values to read of a graph, it is better to take them from the middle part of the curve, as this is where you will have more points per change in y co-ordinate.
* When describing your "plan" in Experiment C, state that the graph you plot will be a straight line through the origin (if this is the case!), of gradient = to an expression which will help you confirm the relationship suggested by the examiner.
* Turning points on graphs require at least 4 points.
* If points near the origin deviate substantially from your line of best fit, point out that for small measurements there is a greater uncertainty.

Experiments Involving Temperature

* Readings should be accurate to fractions of a degree.
* Stir any liquid being heated.
* Insulate the apparatus if possible.
* The thermometer should not be touching the sides of the container it is in, and should be in the middle of the liquid you are measuring the temperature of.
* Precaution: read the thermometer at eye level to avoid parallax error.
* The bulb of the thermometer should be completely submerged.
* Comment on the result obtained being the right order of magnitude.

THANKS A LOT for the notes ,but what do u mean by absolute errors in the uncertainty part.

 

[Jinkglex]

alri

yaar
its really very easy. to calculate the uncertainty just divide the least count of your apparatus by 2. and to calculate the percentage uncertainty put the uncertainty as the numenator, ur calculated value as denominator and multiply by 100.

alright but what is the second uncertainty that we use? i dont understand that part :/ and why do we divide the least count by 2? isnt the least count the uncertainty? :/

 

[syed1995]

A star , asd

Yaar how do you justify the no. of significant figures? I mean I know what to take.. But what will be write in the answer.. tell me the exact wording for rutta

 

[beeloooo]

can you please confirm the questions that are coming?
i have heard the first question is related to newton meter
and im not sure if the second question is related to hookes law or something related to flow of water

flow of water !

 

[recchi26]

Theres no question on heat...my physics teacher is a supervisor at a centre...question is on tubes in wgich we will have to add water and measure volume (thats a guess). The tubes are similar to those at the back of a syringe. And theres a vernier calliper. Most probably theyll ask us to find the volune flow rate of water. And theres a 200ml beaker too. More updates coming soon... And yeah he also said that the appratus would be new for all of us since this appartus has never been used before..

Volume flow rate?

 

[saadamir_95]

are you sure?
some of my friends are saying hookes law and some are saying that a long tube would be connected to a syringe
and flow of water is to be measured either by changing quantity of water or length of tube.
what do you think?

 

[asd]

A star , asd

Yaar how do you justify the no. of significant figures? I mean I know what to take.. But what will be write in the answer.. tell me the exact wording for rutta

For justification of sig fig, I always write that to maintain consistency with the readings of "k" and "l" this reading was taken to the same number of significant figures.
(here, k and l are 2 readings which we took down earlier and they've asked you to justify the sig fig for M, where M is related to k, and l in some way).

 

[A star]

What do we need a BRICK for?
This apparatus is so so weird ...never heard of this before ...this is DAMN confusing! and you tell us to enjoy?
Physics will make me go crazy on day...

i have seen 3 lists of diff aparatuses :/

 

[beeloooo]

i have seen 3 lists of diff aparatuses :/

this is similar to the one i sent u

 

[A star]

this is similar to the one i sent u

yup similar yes but not all the same in 33 physics every one agreed on the list of apparatus

 

[Xeshan16]

Yes, I deleted my post for safety reasons and please also delete your above quoted post of mine inbox me I'll tell you the details.

iNBOX ME TOO