I’ll meet you at your house after school! Not to worry, I’m not talking about me stalking you!

What I am talking about is our next lesson on “Position and Time.” I just gave you a Position, your house, and a Time, after school. –In the last lesson we saw how distance and speed were related. –In this section we are going to use position and time. By the end of this section I am hoping that you will be able to use these techniques to understand how “Acceleration” works. – But more about that later! Let’s look at “Position” first.

What is Position? In Physics, the word “Position” means when something is compared with where it started, and this includes direction! As things move their position changes! If a car leaves your house, it’s position changes. –If it continues to go farther away the position will continue to change by increasing due to the increase in distance from the starting point. If it stops, the position will also stop changing. –On the other hand the position will also be able to decrease if the car begins to change its direction and approach the point at which it started.

This shows the positions of players in a “Scrum.”

I mentioned moving away and moving towards the point at which the car started. I’m leaving something out, what is it? The Distance that it traveled! Distance is an interval of length without regard to direction. You could walk a distance of 10 miles in a circle and end up right where you left off at. You could walk another 10 miles in a zig-zag pattern and only be 5 linear miles miles from your starting point. –Another way of saying linear distance comes from the old pioneer saying, “The way the Crow Flies.” This assumes that the crow flew in a straight line.

Here we can see the distance that this car has traveled in a given time.

Position and Distance are different. If you are 350 miles north of Sylvania in Upper Peninsula of Michigan, that is a statement of your position. If you start the trip back home your position decreases, and when you get back to Sylvania your position is ZERO, even though you have traveled over 700 miles, 350 there and back.

Now let’s look at the “Position vs. Time” graph. This type of graph will show us where things are at different times. –You might think that speed is enough, but speed does not always give you enough information. Let’s go back to the Upper Peninsula of Michigan. I can make it to the Mackinac Bridge in 7 hours with my family. It is 350 miles from my house to the bridge. Therefore you can say that I made the distance with a speed of 50 mph. If I drove that speed on I-75 I would cause numerous accidents and get a lot of sign language thrown my way. I actually had to stop stop twice for “Potty breaks” a total of 30 minutes between the two, and once for “Arby’s,” because they were hungry, and that took another 30 minutes. Now knowing that what was my speed? 6 driving hours divided into the 350 miles to get to my new position equals close to 60mph. What would something like that look like on a graph?

Time and Position graphs See if you can figure out what is going on in following graph.

Try these and see if you can figure out what is going on? The object is standing still at a positive location. Since the slope equals zero it has no movement. The object is traveling at a constant positive velocity. The locations of its position are increasingly positive.

Keep Going! This slope represents a constant negative velocity since the object is traveling in a negative direction at a constant rate. Notice that the locations of its position are becoming less and less positive Time versus Position Quiz