ShmoopTube

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All right here's your Shmoop du jour brought to you by skateboarders. They may

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not want you to know it but they're actually physicists in training. Check [Skateboarder does a trick]

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out the following diagram dude.. All right a ball rolls down the ramp shown above, a

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group of students are tasked with measuring the total energy of the system. [Diagram of the experiment]

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Which of the following measurements do they need, select two answers. And here

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the options. (Quickly reads through the text) Well they're all kinds of

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energy, potential energy, kinetic energy, nuclear energy and the most powerful of [Examples of the energy types are shown]

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all sugared up little-kid energy! To find the total energy [Kids running round a garden]

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of a system we need to take its potential energy and its kinetic energy

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and add those up to show the total mechanical energy. Well we can see that

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there's a relationship between these two forms of energy and in an isolated [Two people with 'potential energy' and 'kinetic energy' tshirts on]

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system the total energy cannot change. It's called the law of conservation of energy

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and even the best legal team in the world couldn't help us break that law. [Judge uses a gavel]

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Now we know that if kinetic energy in the system increases the potential [People on a roller coaster]

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energy has to decrease and vice versa. Well simplify this question which is

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always our goal we can minimize the kinetic energy and maximize the [Big guy with 'potential energy' tattooed on his chest]

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potential energy. So if we just focus on the potential energy of this system when

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the ball is at the top of the ramp and isn't moving we can find the mechanical [Diagram of the ball at the top]

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energy of the system. And the way to find potential energy is to multiply the mass

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by the gravity by the height .We always know gravity so we're left with mass and [Potential energy equation]

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height and hey isn't that what answers (B) and (C) look like, yep those are our

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correct choices. We don't need to know the distance the ball travels and we [A baseball hits an apple and it explodes]

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also don't need to know the acceleration of the ball so options (A) and (D) you're

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just out of the running. Well we're not great at skateboarding so instead we're [Kid has fallen over and his skateboard hits him in the head]

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going to go practice our favorite and safest extreme sport, freestyle couch sitting. [Guy sat on the sofa eating chips]

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