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# C4 Vectors. The axes? watch

1. Hi there,

I was just working through the vectors topic on MyMaths, and when they drew their three dimensional vecors, they had the x axis in the normal place, the y going into the page, and the z where the y normally is.
Is this a convention for vectors?
I always just (probably wrongly) assumed the z axis goes into the page?

Thanks.
2. (Original post by IndyJK9)
Hi there,

I was just working through the vectors topic on MyMaths, and when they drew their three dimensional vecors, they had the x axis in the normal place, the y going into the page, and the z where the y normally is.
Is this a convention for vectors?
I always just (probably wrongly) assumed the z axis goes into the page?

Thanks.
This is one convention, the other is as you say, it doesn't really matter.

EDIT: Except the z-axis comes out of the page - didn't read the post properly :/
3. (Original post by joostan)
This is one convention, the other is as you say, it doesn't really matter.
Ok, thank you.
4. erm, it does matter. Get it wrong and all your angles will be incorrect.

Try telling a pilot where to go in 3 -dimensions with an arbitrary choice of axis! lol.
5. Could make the vector product interesting too.
6. Oops see edit
7. (Original post by joostan)
This is one convention, the other is as you say, it doesn't really matter.

EDIT: Except the z-axis comes out of the page - didn't read the post properly :/
Ok, that would make sense, thanks again.
8. (Original post by IndyJK9)
Hi there,

I was just working through the vectors topic on MyMaths, and when they drew their three dimensional vecors, they had the x axis in the normal place, the y going into the page, and the z where the y normally is.
Is this a convention for vectors?
I always just (probably wrongly) assumed the z axis goes into the page?

Thanks.
There isn't a fixed convention, but it is usual for the x,y,z axes to form a right-handed set. In other words, imagine you are holding a screw in your right hand. If you turn your hand from the x axis to the y axis, then the screw should travel into the direction of the positive z-axis.

Hope that makes sense - I'm not in the habit of carrying a screw round with me, and normally they screw into walls!
9. It's all a matter of convention. Make sure, however, that all the axes are going in the right direction (positive axes going clockwise from x to y to z when looking down from the origin).
10. Mei seem to have a habit of either choosing really awkward orientations for the axes, or not sticking with the same way between papers so if you're with them watch out for that (not sure about other exam boards)

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