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VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Mathematical Methods CAS => Topic started by: Andiio on September 16, 2011, 11:33:38 pm

Title: Signed Area
Post by: Andiio on September 16, 2011, 11:33:38 pm
If a question asks you to find/calculate the 'signed area' of a curve, is it simply a one-step integration? (i.e. ignoring +/- areas, so finding the magnitude)

Title: Re: Signed Area
Post by: paulsterio on September 16, 2011, 11:36:43 pm
Yes, its just the integral between the two bounds
It can have a negative value

Also, no, you're not correct in saying finding the magnitude, finding the magnitude is finding the area, here you are NOT finding the magnitude
Title: Re: Signed Area
Post by: abeybaby on September 17, 2011, 12:50:26 am
Does signed area have units?
Title: Re: Signed Area
Post by: paulsterio on September 17, 2011, 07:27:47 pm
Does signed area have units?

well, if you consider that both distance and displacement are measured in meters, and distance is effectively the unsigned area under a velocity-time curve and displacement is the signed area, I think that it's fair to say signed areas would have units?
Title: Re: Signed Area
Post by: abeybaby on September 17, 2011, 08:50:40 pm
but then would you say something like, the signed area is -5 square units? cos that sounds weird to me...
Title: Re: Signed Area
Post by: BlueSky_3 on September 17, 2011, 08:53:39 pm
Based off a reliable source, signed area does not include units according to VCAA.
Title: Re: Signed Area
Post by: paulsterio on September 17, 2011, 09:16:31 pm
but then would you say something like, the signed area is -5 square units? cos that sounds weird to me...

you make a good point....hmmm :)

Based off a reliable source, signed area does not include units according to VCAA.

oh, thanks for that :)
and btw, what's the source? :)
Title: Re: Signed Area
Post by: b^3 on September 17, 2011, 09:18:23 pm
but then would you say something like, the signed area is -5 square units? cos that sounds weird to me...

you make a good point....hmmm :)

Based off a reliable source, signed area does not include units according to VCAA.

oh, thanks for that :)
and btw, what's the source? :)
The way I look at it is that signed area does not have units, but when interpretting a problem, in the context of the problem units may be needed, i.e. -5 could be the displacement or velocity, it's just in the opposite direction.
Title: Re: Signed Area
Post by: BlueSky_3 on September 17, 2011, 10:22:22 pm
The source is a certain Dr.G who happens to be an experienced methods and specialist maths teacher at Melbourne High School.
Title: Re: Signed Area
Post by: paulsterio on September 17, 2011, 11:14:26 pm
The way I look at it is that signed area does not have units, but when interpretting a problem, in the context of the problem units may be needed, i.e. -5 could be the displacement or velocity, it's just in the opposite direction.

Hmm, alright then, I've never really thought about it :P haha!

and you mean -5 could be the displacement or distance? :P

The source is a certain Dr.G who happens to be an experienced methods and specialist maths teacher at Melbourne High School.


Oh right then, I guess no units it is :)
Title: Re: Signed Area
Post by: david10d on September 18, 2011, 12:38:20 am
It seems like Dr G and Dr He think alike.
Title: Re: Signed Area
Post by: paulsterio on September 18, 2011, 01:23:22 am
It seems like Dr G and Dr He think alike.

Well Geeeeee and Heeeeeee rhyme
G and H are next to eachother in the alphabet
They're both have doctorates in areas of mathematics
They're both acclaimed in the field of maths
They're both known for setting hard questions
LOL! =.=" any more similarities? :P
Title: Re: Signed Area
Post by: b^3 on September 18, 2011, 09:50:34 am
The way I look at it is that signed area does not have units, but when interpretting a problem, in the context of the problem units may be needed, i.e. -5 could be the displacement or velocity, it's just in the opposite direction.
and you mean -5 could be the displacement or distance? :P
Well bringing physics into this, distance is a scalar quantity, displacement, velocity, acceleration are vector quantites, so they have direction associated with them. The signed area will give you displacement not distance as it takes away the area underneath, this is the time when it is travelling in the opposite direction and so will give displacement not distance. To get distance you have to split the intergral up .....blah blah (you know what I mean). With velocity, it will just be the area under a acceleration time graph (although I don't think we get those in methods). The negative velocity, say -5, would mean it is just travelling in the opposite direction.
Title: Re: Signed Area
Post by: paulsterio on September 18, 2011, 11:38:00 am
yeah, b^3, I realized that I misinterpreted what you said the first time, my bad :)

but yeah, that's how I understand it as well, so I guess we're clear on this now :)