AS Physics Practical - Paper 34

[A star]

i was right balancing and heat question but what in the world doo we need a round nail :O

 

[beeloooo]

i was right balancing and heat question but what in the world doo we need a round nail :O

bro inbox me!

 

[Usman Ismail]

The coming exam will use these:
Uniform wooden strip 均匀的木条
String 线
Stand 铁架台
Round nail 圆钉
Newton-meter 0.1N (0-10N) 牛顿力计
Mass hanger 质量挂钩
Modelling clay 粘土（橡皮泥）
Meter rule 1mm 米尺
Pivot 支点或支架
Spacing 间隔或空挡
Clamp 夹子
Flexible plastic tube 柔性塑料管
Scissor 剪刀
50ml plastic syringe 塑料注射器（50ml）
Nozzle 喷嘴
Plunger 活塞
2ml graduation 刻度（2ml）
Bowl 碗
Tray 托盘
Blu-tack 胶水
Vernier caliper 游标卡尺（0.1mm）
Beaker 烧杯
Jug 壶
Paper towel 纸巾
Stopwatch 秒表（0.1s）

are you 100% sure about this?

 

[TheBeast]

hey fellas, when drawing a graph, can u plot points on the axis? and can u draw the graph in landscape?

 

[recchi26]

i was right balancing and heat question but what in the world doo we need a round nail :O

Do you know which paper from which year have the questions about balancing and heat?

 

[stareaj]

Any pp question on moments
Can u please tell me tgeyr

 

[stareaj]

Whats the percentage uncertainty of newtonmetre

 

[stareaj]

How many sig fig should we givefor newton metre

 

[Syed Sameer]

Its +/- 0.5N, if the least coount is 1 N ...

 

[pakiboy]

i was right balancing and heat question but what in the world doo we need a round nail :O

There is no heat dude

 

[mrnt3250]

I don't think any paper has the same questions.
So practice all possible ways..

 

[crook2000]

How about the last 8 scores for moments

 

[A star]

There is no heat dude

we use bowl for cooking food in phy

 

[mrnt3250]

How about the last 8 scores for moments

What do you mean??

 

[Jinkglex]

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

 

[syed1995]

i was right balancing and heat question but what in the world doo we need a round nail :O

You will heat without a bunsen flame or a matchstick? WITH A BOWL? AND WHAT ABOUT A THING CALLED A Thermometer ?

 

[A star]

You will heat without a bunsen flame or a matchstick? WITH A BOWL? AND WHAT ABOUT A THING CALLED A Thermometer ?

mayb idk man :/ well ihope no heat comes :/

 

[samiaaaaaaaaaaaaahhh]

Whats the percentage uncertainty of newtonmetre

yeah what is it?

 

[pakiboy]

we use bowl for cooking food in phy

Where is the thermometer then ????

 

[The Munchkin]

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.

Me too pleaseeeeee ...