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06-33 Kinetic Energy Solution

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    Now, you could have solve this problem using the equation of motion that we learned about in unit 2
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    or you could have use our new super cool technique of the work energy theory,
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    which is how I'm going to solve this one.
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    For work energy theory, first we need the total work and that is given by this equation.
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    Well, let's look at the forces on the ball.
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    Well, this is an easy one, there is only gravity pointing downwards.
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    Okay, and Δx, well, we're just going to use this distance 57 meters.
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    W = mg * 57 and that is also equal to the change in kinetic energy.
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    And notice that an amazing but necessary thing happens, the mass cancels out.
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    I can also multiply both sides by 2.
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    Oh and don't forget that the initial velocity was zero since it was released from rest,
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    and now, we have this equation.
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    I just take the square root of both sides, and I get the final velocity of 34 m/s.
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    So, now, we have another tool to solve this problem.
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    We'll find there's actually places where this tool will solve problems that our previous tools couldn't.
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    I think I teased you a little too much when I said,
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    I don't know what energy is, but I know what energy does.
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    Let's dove into that a little more deeply.
Title:
06-33 Kinetic Energy Solution
Description:

All units in this course below:

Unit 1: http://www.youtube.com/playlist?list=PLF79FCD2E20F4F9FC
Unit 2: http://www.youtube.com/playlist?list=PL0E63503E8232BB23
Unit 3: http://www.youtube.com/playlist?list=PL9BF147060D26ADF6
Unit 4: http://www.youtube.com/playlist?list=PLDB3B73A8BCD831C3

Join the class at http://www.udacity.com to gain access to interactive quizzes, homework, programming assignments and a helpful community.

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Team:
Udacity
Project:
PH100 - Intro to Physics
Duration:
01:02
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