## ← 04-01 Two Dimensional Motion

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Showing Revision 1 created 07/03/2012 by Amara Bot.

1. Welcome back; now, it’s time to talk about 2-dimensional motion
2. and this is where things get really interesting.
3. So far, we’ve only talked about 1-dimensional motion and that motion in a straight line
4. either purely up and down motion or purely left and right motion.
5. But what happens when we have some combination?
6. Well, then we get the motion with—this is the sort of motion that describes
7. a cricket ball as it bounces towards the batsman or an arrow as it sails towards it’s target
8. or a parachutist who has just jumped out of a plane.
9. Now, before we talk about our modern day understanding of 2-dimensional motion
10. and in fact Galileo’s understanding, let’s talk about what Aristotle thought of 2-dimensional motion.
11. In Aristotle’s mind--and this is Aristotle over here of course--
12. objects, for example, a ball thrown into the sky moving in a straight line
13. until they ran out of what he called impetus.
14. At that point, after the fall straight down and land somewhere on the ground.
15. Now, before I continue, why don’t you try this.
16. Throw a small object like a coin or a pencil in front your field of view, and look at what you see.
17. It’s actually really difficult to see what’s going on.
18. In fact, it wasn’t until Galileo came around that the true path of an object
19. in 2-dimensional motion was known.
20. That path is what called a parabola. So, we know that 2-dimensional motion is parabolic.
21. And so what? Parabolic is just a word. What does that mean?
22. In fact, can we use this word to somehow describe 2-dimensional motion mathematically?
23. In physics, prediction is power, and what I mean by prediction is, can we develop
24. our understanding of motion in such a way that we can explain and predict mathematically?
25. How an object will move before we actually throw that object, let's say?
26. We can and that’s what we will do in the rest of this unit.