Technical Problem Solving C

[Phenylethylamine]

How important will significant figures be? Do most event coordinators judge on that, or would it be better to give more exact answers?

Note that your "more exact answers" are not actually any more exact (by which I think you mean precise) than if you give the correct significant figures. Significant figures exist for a reason: they are all the precision you actually have in your measurements. Any additional digits are meaningless, because you simply haven't measured to that level of precision.

For example, if you measure one side of a rectangle to be 1.7 cm long, and the other side to be 4.3 cm long, you can multiply those values to get that the area is 7.31 cm^2 – but that 1 there in the hundredths digit is meaningless. Your original measurements weren't precise enough to tell if it's actually 7.28 cm^2 or 7.34 cm^2 or anywhere in that range, so the best you can do – the most exact answer you can give – is that the area is 7.3 cm^2.

If that doesn't give you an intuitive feel for why significant figures are actually meaningful (and not just some set of rules we have to follow to make our answers look nice or something), imagine that after the 2010 census, the US government announced that the population of the United States was 312,950,746 people. Do you really think they know the population to the nearest individual person? Maybe they know to the nearest thousand people (which is still a pretty impressive feat, given how hard it is to count population), but it's clearly ridiculous that they could come up with a meaningful number all the way out to the units digit.

Now let's say their method of conducting the census gave them a bunch of other data that they then combined to get the total number, and let's say this data was in a form that, when all multiplied and added together with exact numbers, gave them that value of 312,950,746. This is where significant figures come in. Knowing that their original data only contained, say, six figures of precision, they would know that 312,950,746 – while probably in the ballpark of the exact value – was not a meaningful way of representing the population of the United States based on their census count. If their original data had six figures of precision, they could say that there were about 312,951,000 people in the United States (thank you, Wikipedia), meaning that there were anywhere from 312,950,500 to 312,951,499 people in the United States at the time of the census.

[eta150]

I've got a couple of questions for people with more experience in this event:
1. What is packing constant, and how do you use it? I'm talking about marbles in a jar questions
2. If they ask you to make a shape out of some material to get it as close as possible to a certain weight, should you have a density memorized? Or is there some other way?

[Schrodingerscat]

1. I would assume that the packing constant would be the ratio of the volume of marbles to the volume of a cluster of marbles. so if they had a 0.75 packing constant, a 100cm^3 jar would contain 75cm^3 of marbles and the rest air.
2. You should not (if run ideally) need to have any densities or constants memorized, as they should either be provided or available to be measured using providing equipment.

[nendawen]

For technical problem solving do they have use TI probes at the regional competition?

[Schrodingerscat]

For technical problem solving do they have use TI probes at the regional competition?

The rules only appear to require probes at state level and above, although the topics are limited at all levels.

[Phenylethylamine]

For technical problem solving do they have use TI probes at the regional competition?

The rules only appear to require probes at state level and above, although the topics are limited at all levels.

In past years, I've only seen TI probes at Nationals. At Nationals, they were at pretty much every station, though.

[butter side up]

I recently encountered a question with a diagram set up like a square, with Q- or Q+ in the corners. I can't remember what it was called, but it had something to do with charges. Does anyone know what this is called, and how one goes about doing those problems? (I tried doing a Google search, but it is challenging to do when you don't know what it is called.)

[EastStroudsburg13]

I saw that, it was on the Tiger test. It looked like an AP problem to me, so you may want to check with a physics teacher to see how they can help you. I'm not entirely sure what it's called, and I haven't had AP Phys; if not for that AP Chem question on the test, we probably wouldn't have done very well.

[GoldenKnight1]

I saw that, it was on the Tiger test. It looked like an AP problem to me, so you may want to check with a physics teacher to see how they can help you. I'm not entirely sure what it's called, and I haven't had AP Phys; if not for that AP Chem question on the test, we probably wouldn't have done very well.

It is a physics problem but does not seem to follow this year's rules for TPS.

[gigaboo]

My test was on finding density of things and acceleration and vertical/horizontal displacement while jumping. We finished half of the test and still got first.