There are many parts of movement that we cannot see. Sure, you can watch something move, but once it has stopped, there is nothing left over. You might see tire marks on the road or waves in a lake, but they go away after a while. Then you might not know where something has gone. To learn about the parts of movement we cannot see, I am going to cover you in purple powder so when you move, you will leave a trail like an airplane. FWOOM! There. Now I am going to fire you out of a cannon. Put on this helmet. I will light the wick. Ssssssssssssssssss . . .
Wait, nobody said anything about a cannon!
michael ely / Circus Tents
KABOOM! You shoot out of the cannon like a bullet, making a curved purple line right through the circus tent! Now would be a good time to tell you that lines of motion have two important parts. The first one is
direction, or which way you are going. This is what makes a nice neat line of purple dust across the tent. Speaking of direction, look where you are headed. You're going right toward a trampoline.
Now that I've got direction in my life, just looking for a trampoline.
BOING! You hit the trampoline and bounce up, making a new line. The second part of a motion is its magnitude.
Magnitude means how strong a force is or how fast a speed the object is going. Every line has a beginning and an end. Your first line was pretty long, since you were fired out of the cannon super fast from one side of the tent to the other. The one you make bouncing up from the trampoline has a smaller size because you have slowed down a little. It still looks pretty cool, though. Oh! Look up! Grab that swinging bar.
Now if I can just find the swinging bar.
Eric Dufresne from Trois-Rivières, Canada, CC BY 2.0 , via Wikimedia Commons
SWISH! You swing through the air on a trapeze bar, making another line. Just like the last two, this line has a value. A
value is a number or how much something is worth. As you swing along, we can add up how many feet you swing. When you reach the end, we will look at your purple trail of dust you made. Then we can add up the value of the line you just made, or how far you have gone.
CATCH! You do a flip off the bars and land in the safety net. Come look at what you just did. You made three lines. A
vector is a force with direction and magnitude. You made one shooting out of the cannon across the tent. Then you made another in a different direction, bouncing on the trampoline. Finally you made another one while swinging on the bar. Great job. This must not be your first time at the circus.
Most of the time, we cannot see the path something has moved along. Things that move do not tend to leave trails. By dunking you in purple powder, we can see all the vectors you made through the air. We can see the way you went and how far you moved. If we look at your vectors as a drawing, it looks like . . . a broken caterpillar. Do you think you can draw something better? Wait, why are you mad? Oh, sorry. Next time I will give you more warning before I fire you out of a cannon.
References:Physics 4 Kids. "Vector Basics" Physics 4 Kids, 2009. <
http://www.physics4kids.com/files/motion_vectors.html>
Math Is Fun. "Vectors" Math Is Fun, 2010. <
http://www.mathsisfun.com/algebra/vectors.html>