Today’s Post is in many ways a back-up and regroup post. I think this will be very easy for most people. However, I needed to build a good foundation of ideas before we proceed head-long into the complicated stuff where we have already been. Also, this is probably a good post for someone that has a child in school and is having trouble really understanding basic mathematics.

I have received many questions about an old post that I did concerning a pontoon boat made out of PVC pipe and how I estimated buoyancy. I am going to revisit that again only this time we will be looking at using a plastic barrel for the pontoons. It will be much less expensive but again I have not actually built one. (And, I have no intentions of building one.)

To really explain all the calculations we will need to talk about vectors, trigonometry, polar coordinate system and some other subjects. Eventually I will show you how to do all these calculations using a simple spread sheet. If you know the math already, I apologize, but I seem to have several people that do not. It will not be long before we move along.

I am doing this in video format because video seems to have a longer longevity than the written version.

There is not a lot to summarize about this video except the following.

The horizontal axis is called the X axis, The positive direction is to the right of the X, Y cross point. Moving left of that cross point is the negative direction.

The vertical axis is called the Y axis and the positive direction is up above the X,Y cross point. Moving below of the cross point is the negative direction. (Memory tool: You are digging a hole… and going in reverse.)

When writing a point location ii is written in the form of (X, Y) where X is the X value.

The cross point of the two axis is point (0,0) and is called the origin.

There are four quadrants. These are:

- Quadrant I: The upper right corner and both X and Y are positive.
- Quadrant II: The upper left corner and X is negative and Y is positive.
- Quadrant III: The lower left corner and both X and Y are negative.
- Quadrant IV: The lower right corner and X is positive and Y is negative

Notice these quadrants start above the positive side of the X Axis and are counted counter-clockwise. This counter-clockwise motion will be important about 2 videos from now.

The video is located here:

There are other videos and articles out on the net about the Cartesian Coordinate system and I would encourage you to give them a look if you want to know more about this important concept.

As always I hope you find this video useful and informative.

Gary

“The Cartesian Coordinate System Part 1” by Create-and-Make.com is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

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