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So let us look at this example, what I've drawn here is a roller coaster, so the blue line is the

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path that the roller coaster will follow from a high point at 20 meters at point A to a lower point

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at point B.

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Initially at point, the roller coaster is stationary, doesn't move, so it has zero kinetic energy,

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but because it is at a height of 20 meters, it has a potential energy that we can calculate because

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we know the mass of this roller coaster cord is 300 kilograms.

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Now, the question is, what is the velocity of this roller coaster when it reaches point B, we can

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ignore friction and we can ignore the air resistance.

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So let us investigate this court in terms of its energy at point and at point B, so at point A. the

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question stated that the court is stationary.

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So we know that the kinetic energy, the first position will be zero.

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But it is at a height of 20 meters relative to point B, so we can calculate a potential energy which

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is equal to engage, which is equal to 300 multiplied by nine point eight, one multiplied by twenty,

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which gives us thirty eight thousand eight hundred and sixty joules.

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That's the same unit for energy.

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At point B.

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It has now reached.

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A zero distance from the reference line, so the potential energy will be zero, but it will have a

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certain velocity.

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So there will be a kinetic energy and that kinetic energy is calculated by one half in the square.

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Now, we don't know what is V that is what we want to calculate.

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So let us write down the principle of energy conservation, kinetic energy one plus potential energy.

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One is kinetic energy two plus potential energy to.

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So zero, this is a point a plus.

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Fifty eight thousand eight hundred and sixty is equal to one half in the squared plus zero.

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That would be at point B because we know the mass.

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We can substitute that for him and we can solve for the velocity at point B to be nineteen point eight

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meters per second.

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This is a fairly simple example, but it illustrates the principle and the principle is that the total

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amount of energy in the system stays the same, but it is exchanged between different forms.

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It is exchanged between kinetic energy and potential energy.

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And so at point A. we knew what was the total amount of energy because it was only potential energy.

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And at point B, we knew the potential energy is zero.

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So that energy at point B was the kinetic energy and therefore we could solve for the velocity of.