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Postby steeljam » Sat Jul 02, 2005 11:23 pm

Kelshandra wrote:I havn't heard this! As someone who did Year 12 physics a number of years ago the exam really wasn't that hard in the first place! And I did not encounter a single person, then or since, that found the concept of 9.8m/s/s that difficult a number to deal with :shock:
That is the reason why God invented calculators, after all :D (and they get to use graphic's calculators nowdays, unlike in my time when it was only the standard scientific calculator)

In my days is was tables and the slide rule. I still have the slide rule I used in University for both pure and applied maths.
The smell of the plastic still invokes the terror of the final exams.
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Postby Kiyomi » Sat Jul 02, 2005 11:28 pm

steeljam wrote:In my days is was tables and the slide rule. I still have the slide rule I used in University for both pure and applied maths.
The smell of the plastic still invokes the terror of the final exams.

While it's nice to have a calculator a good portion of the time I've done a problem by hand before I remember I could use a calculator. A fact which saved me on several exams when I forgot to bring one ;-) I do have a horor of trying to do math through computer programs, I almost failed my second math class in college because I couldn't get the computer to solve the problem for me :shock: Ironically I was perfectly capable of working the problems out by hand so my test grades saved me, and obviously I am very computer literate but I failed every bit of homework from that section in spite of hours with those stupid math programs trying to get them to work.
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Postby Kelshandra » Sat Jul 02, 2005 11:29 pm

Slide rule.... I think I saw one of those at the museum once.... :twisted:

Actually, when I did physics the exam was really easy then. Don't know if the rules have changed now, but when I did it, you were allowed to take in a A4 piece of paper into the exam with whatever you wanted written on it- and you were given all the formulas required in the paper anyway (and being the smartarse that I was, I wrote down a list of numbers and letters to see if the examiners would notice: 1:A, 2:D etc. And a friend of mine who knew some Arabic wrote down several paragraphs on his in the left over space :D)
The thing is, once they hit uni the baby treatment goes out the window causing all the first year students to go into shock, so I don't think that treating them like idiots in Year 12 is really going to help them :shock:
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Postby Fendetestas » Sat Jul 02, 2005 11:36 pm

Well, in 1897 an Indiana Bill set for pi values ranging from 9.24 to 3.2. For example:

It has been found that a circular area is to the square on a line equal to the
quadrant of the circumference, as the area of an equilateral rectangle is to the square on one side.


That is, pi = 9.24

that the ratio of the diameter and circumference is as five­fourths to four


i.e., pi=16/5=3.2. There are two more values for pi implied in the bill, that showed how to square a circle.

The bill was later killed by the Senate, because a real mathematician happened to be there, lobbying for an Indiana Academy of Science.
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Postby Doc Brown » Sun Jul 03, 2005 07:56 am

steeljam wrote:In my days is was tables and the slide rule. I still have the slide rule I used in University for both pure and applied maths.
The smell of the plastic still invokes the terror of the final exams.


We were free issued slide rules and tables when we started at the Grammar school, I still have mine although it is a bit batterred after all the table top cricket. :D

For the exams calculators were banned (probably because not many people had them), but this made exams easier as they tended to use numbers that gave nice round answers. If answers started coming out anything else it was a good indicator that you should go back and check your calculations. :D
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Postby Colin » Sun Jul 03, 2005 07:57 am

Kiyomi wrote: While it's nice to have a calculator a good portion of the time I've done a problem by hand before I remember I could use a calculator. A fact which saved me on several exams when I forgot to bring one ;-)


... and therein lies the nub of a potentially serious problem ... over-reliance on calculators, computers, etc ...

My wife, once a senior nurse was horrified on a daily basis by junior nurses using calculators to work out drug dosages (for chemotherapy on kids with cancer ... you know the kind of thing ... the correct dose is hopefully theraputic, under or ... worse ... overdosing KILLS) and not recognising that the answer provided by the calculator is WRONG ... mainly by factors of 10 :shock: ... because they had not input the data correctly.

Now this is why drug rounds usually have two nurses ... one to calculate, the other to check. But when they are both from the current generation who are so reliant on calculators & computers that they don't understand the basic maths and therefore don't recognise the obvious errors caused by wrong data input ... :shock:

Mark my words ... when the power runs out, no-one will be *able* to survive, even if they wanted to ... and ants will inherit the Earth.
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Postby Susan Sto Helit » Sun Jul 03, 2005 08:40 am

When I did my GCSE maths, we had a calculator paper, and a non-calculator paper, so they could test our mental maths ability as well as using the calculator. When it came to A-level, they included questions that couldn't be done on a calculator. We weren't allowed graphical calculators.

What did always get me though, was that for physics gravity was 9.81m/s/s, but for maths we had to use 9.8. I kept getting the wrong answers in maths, because I used a more accurate value.
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Postby Fendetestas » Sun Jul 03, 2005 08:55 am

Susan Sto Helit wrote:What did always get me though, was that for physics gravity was 9.81m/s/s, but for maths we had to use 9.8. I kept getting the wrong answers in maths, because I used a more accurate value.


The 981 cm/s^2 vale is quite silly sometimes. It's the value at the latitude of Paris. Some high school textbooks use this value in Spain, where the effective g is a bit lower. The value for Madrid is 980.0 cm/s^2, 980.3 cm/s^2 in Barcelona and 979.9 cm/s^2 in Seville. The value at Madrid is quite accurately the «simpler» value of 9.8, so we were doing the opposite of the Australians, i.e., using an «uglier» number than necessary.

Note: The value of g varies with latitude because of centrifugal effects due to the rotation of the Earth. It's weakest at the Equator (978 cm/s^2) and strongest at the Poles (983.2 cm/s^2). The oblateness of the Earth also contributes.
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Postby Cara » Sun Jul 03, 2005 08:59 am

Fendetestas wrote:The 981 cm/s^2 vale is quite silly sometimes. It's the value at the latitude of Paris. Some high school textbooks use this value in Spain, where the effective g is a bit lower. The value for Madrid is 980.0 cm/s^2, 980.3 cm/s^2 in Barcelona and 979.9 cm/s^2 in Seville. The value at Madrid is quite accurately the «simpler» value of 9.8, so we were doing the opposite of the Australians, i.e., using an «uglier» number than necessary.

Note: The value of g varies with latitude because of centrifugal effects due to the rotation of the Earth. It's weakest at the Equator (978 cm/s^2) and strongest at the Poles (983.2 cm/s^2). The oblateness of the Earth also contributes.


Wheeeeeeeeeeeeeeee straight over my head.................
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Postby Darren » Sun Jul 03, 2005 09:06 am

[rant]

There's nothing fundamentally wrong with doing the rounding, as long as you're aware that you're doing it, and accept that the answer you get from it will then be an approximation to the real one.

Nature sets the value of fundamental constants like g, and last time I checked Mother Nature didn't take petitions from anyone, even (or perhaps especially) education officials as to their values, or changing them. They can say g or whatever has whatever value they like, it won't make the apple fall any faster or slower onto Newton's head.

As to the reliance on calculators especially, it has been very noticable to me over the years as I've taught A-level undergraduate fizzyx and on the odd occasion mathematix too. As Colin rightly says, you get the GIGO effect, garbage in, gospel out. I have literally had an undergraduate turn around to me and say "but my calculator said so, so it must be true" (frighteningly a verbatim quote).

Arguably using them does prevent miscalculations, which anyone doing long/complex calculations could occasionally make when doing them in their heads. As stated though the problem is when they aren't using the calculator for convenience, but because they can't do it any other way. I often use a calculator, but I always tend to in parallel do the calculation in my head (at least approximately) as a sanity check (the sanity of the answer, not my own as that would always fail). This is the part that the nurses in the example are missing, hence they need two of them (and then due to the system that is still not as secure as it should be).

At the end of the day it's back to having exams in the past that you could actually fail, and exams that you had to know something (and woe betide actually understand as well rather than just repeat parrot-fashion) to get a decent grade in (and not be able to get an A-grade by writing your own name correctly on the paper, Ponder Stibbons style).

[/rant]
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Postby steeljam » Sun Jul 03, 2005 09:36 am

Fendetestas wrote:
Susan Sto Helit wrote:What did always get me though, was that for physics gravity was 9.81m/s/s, but for maths we had to use 9.8. I kept getting the wrong answers in maths, because I used a more accurate value.

The 981 cm/s^2 vale is quite silly sometimes. It's the value at the latitude of Paris. Some high school textbooks use this value in Spain, where the effective g is a bit lower. The value for Madrid is 980.0 cm/s^2, 980.3 cm/s^2 in Barcelona and 979.9 cm/s^2 in Seville. The value at Madrid is quite accurately the «simpler» value of 9.8, so we were doing the opposite of the Australians, i.e., using an «uglier» number than necessary.
Note: The value of g varies with latitude because of centrifugal effects due to the rotation of the Earth. It's weakest at the Equator (978 cm/s^2) and strongest at the Poles (983.2 cm/s^2). The oblateness of the Earth also contributes.

I used to work for a company that refined precious metal. Gravity was different in various parts of the refinery which was half a mile across. It was important to get the scales properly callibrated otherwise we would be looking for losses worth hundreds of pounds.
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Postby Pat » Sun Jul 03, 2005 07:09 pm

Colin wrote: But when they are both from the current generation who are so reliant on calculators & computers that they don't understand the basic maths and therefore don't recognise the obvious errors caused by wrong data input ... :shock:

Two examples from my life spring to mind: I once went into Tandy for some components. I bought 6 different things, each less than a pound.
Guy on till:That'll be 6.54
Me: No, it isn't.
GOT: The till says 6.54
Me: The till's wrong.
GOT: How much should it be?
Me: I've no idea, but it can't be 6.54. Six items each less than a pound can't add up to over 6 pounds.
He wouldn't accept it - had to get the manager.

I have two kids. On one occassion, I bought some sweets for each: I can't remember, exactly what, but let's pretend 2 Mars bars, 2 packets of Buttons and 2 cans of Coke.
Girl on Till: That's 2.71.
Me: No, it isn't. It can't be an odd number of pennies.
Again, it took a lot of time to convince her the Magic Counting Box wasgiving the wrong answer.

"Arithmetic isn't important, we all have calculators these days." "Spelling and grammar aren't important, we all have spell checkers and grammar checkers." "Thinking isn't important, we all have oh dear the battery has run down..."
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Postby Colin » Sun Jul 03, 2005 07:20 pm

Darren wrote: This is the part that the nurses in the example are missing, hence they need two of them (and then due to the system that is still not as secure as it should be).


My wife's point exactly! Sue always did the approximate calculation in her head and used a calculator (or even a written down longhand calculation) to get the correct dosage ... and was thus able to see that the 'calculated' result was in the right 'ball park' and therefore (probably) correct.

Most of her younger junior nurses were not capable of doing the mental arithmetic 'approximation' because they hadn't be taught how to do it ... :shock:
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Postby Darren » Sun Jul 03, 2005 07:37 pm

Why is this suddenly making me feel old? And maybe even a little wise?

Nah, just old...
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Postby Colin » Sun Jul 03, 2005 09:50 pm

Darren wrote:Why is this suddenly making me feel old? And maybe even a little wise?

Nah, just old...


Darren ... you have no idea what 'feeling old' really means ... trust me! :wink:
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