Let's make a Kung fu movie! You can be the hero. I will be the bad guy. Let me just put on all black . . . There. Now, if you have ever seen a Kung fu film, you know that things get very silly. People do many flips, run across water, and even fly. Kung fu movies don't follow the laws of the Earth, but it will be fun to make all of your movements bigger than life so we can see what you can really do. So when you punch me in the last scene (a fake punch, of course), I will fly across the set and crash through a building. And hey, we might learn some science too.
It's night. The moon is shining. We are in a quiet town. It's fight time. I try to sneak up behind you, but you turn around and punch me right in the chest! (Remember, we are only acting.) Force
is a push or pull on something. In other words, I go flying across the town from the force of your punch. A force could be anything from the small effort it takes to open a book to the large effort it would take to lift a car. Your punch lies somewhere right in the middle.
Did someone say they needed a lift?
That was some punch! My body flies backwards like a leaf in the wind. We can use magnitude
, or a number to show how much of something there is. In this case we can use it to show how big of a force you used to hit me. It's the size of the energy, strong or weak. Because we are in a movie, everything is going to be bigger. So the magnitude of force in that punch was huge! I'd say it was more like a big wave or a bullet train than a punch. Have you been working out? Oh, right. I keep forgetting. This is just a movie.
Look out below!
The next shot needs to be a great one. We don't want anyone to be bored. Let's say your punch was so strong that it knocks me into the sky where my body covers the moon before I fall back to Earth again. This means you will need to punch upwards. Direction
means the way something is going or pointing. We could choose any direction, really. You could hit me up into the sky, down into the ground, or across the land. I think sending me up into the atmosphere is the most exciting choice, don't you? If you disagree, just remember that I'm the one getting punched. Hey, I'm the one getting punched.
So what does this all add up to? Okay, it makes a great shot for the movie, but what else? With your punching fist and my flying body, we have just shown one of the most important parts of movement. A vector
is a force that has magnitude and direction. My body made a vector because your punch sent me flying into the sky. Where do I go from here? Oh, right . . . There's only one way to go. . . and it's a long way down there.
Kung fu films, while very silly, are not a bad place to think about how things move. The movies may be over the top, but they still have all of the things one needs to learn about vectors. Oh, you want to know how the movie ends? AAAAAAAAAUUUUUUUUUGGGGGGHHHHHHHH! (Acting.) My body smashes through a small, empty house. Ouch . . . Oh, do not worry. The punch and the crash did not hurt. I just got a splinter.
Is now a good time to start talking about a parachute?
Physics 4 Kids. "Vector Basics" Physics 4 Kids, 2009. <http://www.physics4kids.com/files/motion_vectors.html
Physics Classroom. "The Meaning of Force: Physics Classroom, 2013. <http://www.physicsclassroom.com/class/newtlaws/u2l2a.cfm
Discover. "How to turn your fist into a block-breaking machine" Discover, 2008. <http://discovermagazine.com/2008/the-body/11-turn-your-fist-into-a-blocking-breaking-machine#.UlLWO2...