WEBVTT
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problem. Eight points at 93 you're standing on a
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concrete slab on a frozen lake and as your friend
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, I have to be honest. I'm getting a
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little bit concerned about how you keep getting yourself into
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these situations. But we can have a discussion about
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that after we do some physics. So you start
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walking to the right, say, at two meters
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per second and we want to find out how fast
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the slab starts going in the opposite direction. It
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happens to weigh five times as much as you.
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So this is the center of mass sort of situation
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, because before you start walking, the center of
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mass isn't moving. You know that the that has
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to remain zero, and it also has to be
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your mass times your speed. Apparently you have two
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different styles. And why that I can't make up
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my mind which one I want to use, plus
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the mass and speed of the slab divided by your
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total so we can see this is a weighted average
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of your velocities, which is just the time derivatives
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of the weighted average of your positions so we can
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multiply both sides by this and since this zero.
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It just goes away. Your mass times your speed
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Is that a pool To negative slabs mass times its
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speed. So the slab speed is equal? No
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, it's, you know, speed and direction is
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equal to your mass provided by its mass. Tend
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your speed. No, we know that this is
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1/5 because this is five times your mass and,
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uh, no, you know, multiply everything together
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and we discovered that it's moving a negative zero point
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or meters per second. Try not to hurt yourself
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when you fall off the end of it onto the
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ice. And, uh, this is how fast
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this will be moving away from you.