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Thank you here's Your shmoop du jour brought to you

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by national candy day which is on november fourth We

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consider the other three hundred sixty four days of the

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year to just be well personal candy days to celebrate

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national candy day Willy wonka planes to drop bags of

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sweets from an airplane Unfortunately he forgot to take into

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account the heat produced by drag forces as the bags

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fall through the air Well if the candy bags have

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a mass of zero point four kilograms and reached terminal

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velocity of twenty five meters per second how much heat

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is dissipated due to air drag for every ten meters

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that the candy falls fine here The potential answers While

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dropping bags of candy from a plane sounds awfully generous

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it also sounds like a good way to give people

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brain trauma You've heard of ice cream headaches but candy

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concussions are a new thing We'll assume willy gets lucky

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and doesn't hit anyone directly let's think back to a

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long time ago when we were learning about potential and

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kinetic energies We know that potential energy equals mass times

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height times gravity and we know that kinetic energy equals

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one half mass times velocity squared How do we know

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that Well we studied a bunch of this really cool

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website Uh i can't remember the name but shoot It

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was like shoe or smooth or something like that Anyway

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the moment before an object falls all of its energy

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is stored as potential energy and the moment before an

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object hits the ground All of its energy is in

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the form of kinetic energy moving in a perfectly frictionless

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system The total energy at each of these moments has

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to be equal and put it in terms of work

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A force gravity is applied to an object the bag

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of candy causing it to move the change in kinetic

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energy equals the work done but we don't exist in

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a perfectly frictionless system We exist on planet earth which

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has an atmosphere when we're very grateful for it As

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an object falls through the air it encounters friction also

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known as drag because we're used to rubbing our hands

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together deviously while hatching an evil seem way know that

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friction causes some kinetic energy to transfer into heat energy

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so now we have to throw heat into the equation

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Now our equation shows that the change in potential energy

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equals the change in kinetic energy plus heat When a

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falling object reaches terminal velocity it has stopped accelerating which

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means there's no more change in velocity which means that

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there is no change in kinetic energy So at that

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point all the work being done is creating heat not

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changing the velocity All the change in potential energy equals

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heat energy Now we can plug in the numbers get

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an answer and go eat some candy and start this

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whole questions giving us some serious sugar cravings once an

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object has reached terminal velocity that he created in a

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ten meter fall equals mass times gravity times the change

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in height the mass of the bag equals zero point

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Four kilograms Little round gravity up to ten meters per

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second squared and a change in height is ten meters

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Will the mass shows that the heat created equals forty

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jewels Will answer D is correct We can see that

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once an object reaches terminal velocity whatever the velocity is

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doesn't affect the heat created Get the bags are falling

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at one meter per second or one hundred meters per

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second The work done is the same And if we

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ever see a bag of candy plummeting out of the

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sky and heading for a skull will take cover And

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then we'll scavenge that candy off the ground like animals 00:03:30.67 --> [endTime] That's Just how we roll

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