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Kinetic energy

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MS‑PS3‑5
,
MS‑PS3.A.3
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MS‑PS3.A
Any object in motion has the property of kinetic energy. Simply put, kinetic energy is motion energy. Learn about how kinetic energy is quantified and which characteristics of an object affect how much kinetic energy it has. Created by Khan Academy.

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  • sneak peak blue style avatar for user Raymondarian
    Which is the best and simplest definition way to remember Kinetic and Potential Energy? Not too long, but a very short definition.
    (5 votes)
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  • blobby green style avatar for user georgiajones
    What is a short definition for kinetic and potential?
    (2 votes)
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    • leaf blue style avatar for user hoerschelmanava
      A good way to remember KE is by imagining you are bowling. You push the bowling ball down the lane, forcing your'e energy into it's roll. When the bowling ball hits a pin, and knocks it over, the ball is putting its energy into it. I got 100% on that answer in 4th grade, so I hope it helps.
      1/11/23
      (1 vote)
  • aqualine ultimate style avatar for user Jacob Silva🥶
    When we make new discoveries we need to be able to share them with others. And the first thing we have to do is make sure everyone is on the same page. We do this by using units and frames of reference, which are also called reference frames. We talk about units in another video, so let's look at what a frame of reference is. Let's say this blue box thing is a car, and it's going 45 miles per hour. Someone standing on the side of the road would see it pass at 45 miles per hour. Now, if this yellow truck is going 40 miles per hour someone sitting in the yellow truck would observe the blue traveling at five miles per hour. How could the person on the side of the road see the blue car traveling at 45 miles per hour and a person in the yellow truck see the blue car moving at five miles per hour? This is because both observers are using different frames of reference. So let's go ahead and take a look at that, starting with the speed of the blue car. The person on the side of the road is using their frame of reference of being at rest. So relative to them, the blue car is moving at 45 miles per hour. To the person in this yellow truck, which remember
    (2 votes)
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  • blobby green style avatar for user English, Jaylen2
    how.
    (1 vote)
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  • aqualine ultimate style avatar for user SalomonFofie
    Hello, everyone. m going to explain this for your minds. Let's talk about kinetic energy. Now, kinetic might be an unfamiliar word, but it just comes from a Greek word that means of motion, so kinetic energy is energy from motion. Any massive object that is in motion then has kinetic energy, but how much? First, let's consider some comparisons. This nice rat family, papa, mama, brother, and sister are sitting down to dinner at a long table passing blocks of cheese back-and-forth. Papa rat asks for the cheddar cheese and there are two identical blocks. Brother rat pushes one and sister rat pushes the other, so that the second cheese is traveling twice as fast as the first cheese. Which piece of cheddar cheese do you think has more kinetic energy? Yes, it's the one going faster. Now, papa rat doesn't need both pieces of cheddar, so he eats one and sends one back, along with this small piece of Swiss that weighs half as much as the piece of cheddar. Papa rat has better manners than his children, so he sends them both back at the same speed. Which piece of cheese would you think has more kinetic energy now? Yes, the heavier or more massive object, in this case, the cheddar, will have more kinetic energy. Let's make it a little more complicated. Brother and sister rat are full, so they send the cheeses back for mama rat. Brother rat pushes the larger piece of cheddar and sister rat pushes the smaller piece of Swiss so that the Swiss is going twice as fast as the cheddar. Now, which cheese has more kinetic energy? In fact, it turns out that it's the Swiss in this scenario. Kinetic energy depends on both mass and speed, but the dependence on speed is stronger. This estimation of kinetic energy can be quantified in an equation that lets us calculate kinetic energy exactly. We said kinetic energy depends on the mass and the speed, which we'll write as V for velocity, so we can start with K E equals M times V. But we said that it depends more on the speed, so the velocity here is actually squared. This means that if an object's mass doubles, its kinetic energy also doubles, but if its speed doubles, the kinetic energy actually quadruples. And there's also a constant factor of 1/2 at the beginning of the equation, but we won't go into the details of the math of deriving this today. So, this is the equation for kinetic energy, 1/2 M V squared. Let's apply this equation to our cheesy example. Say the Swiss has a mass of .05 kilograms, which makes the cheddar's mass .1 kilograms. When both cheeses have the same speed, say two meters per second, the cheddar's kinetic energy is 1/2 times .1 kilograms, times two meters per second squared, which is .2 Joules. The Swiss's kinetic energy is 1/2 times .05 kilograms times two meters per second squared, which is .1 Joules, or half the kinetic energy of the cheddar. So we can see that at the same speed, the cheddar has more kinetic energy because it has more mass. But when the Swiss has a speed of four meters per second and the cheddar still has a speed of two meters per second, the Swiss's kinetic energy is now 1/2 times .05 kilograms times four meters per second squared, which is .4 Joules. So now, the kinetic energy of the Swiss is twice the kinetic energy of the cheddar. So we can see that even though the cheddar has more mass the Swiss has more kinetic energy because it's going faster. In summary, kinetic energy is the motion energy of an object. The equation for kinetic energy is 1/2 M V squared. So as mass increases, kinetic energy increases, like the more massive cheddar versus the Swiss, and as velocity increases, kinetic energy increases even more, like the speedy Swiss versus the slower cheddar. Thanks for watching, and I hope you learned a little bit of something.
    (1 vote)
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  • primosaur seed style avatar for user 201131877
    super interesting topic
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  • blobby green style avatar for user DylanV
    i don't have any question
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  • blobby green style avatar for user 133344
    Is there any other types of enrgy?
    (1 vote)
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  • cacteye purple style avatar for user Anne frank
    i dont have any questions
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  • blobby green style avatar for user English, Jaylen2
    which energy is best.
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Video transcript

- [Instructor] Hello, everyone. Let's talk about kinetic energy. Now, kinetic might be an unfamiliar word, but it just comes from a Greek word that means of motion, so kinetic energy is energy from motion. Any massive object that is in motion then has kinetic energy, but how much? First, let's consider some comparisons. This nice rat family, papa, mama, brother, and sister are sitting down to dinner at a long table passing blocks of cheese back-and-forth. Papa rat asks for the cheddar cheese and there are two identical blocks. Brother rat pushes one and sister rat pushes the other, so that the second cheese is traveling twice as fast as the first cheese. Which piece of cheddar cheese do you think has more kinetic energy? Yes, it's the one going faster. Now, papa rat doesn't need both pieces of cheddar, so he eats one and sends one back, along with this small piece of Swiss that weighs half as much as the piece of cheddar. Papa rat has better manners than his children, so he sends them both back at the same speed. Which piece of cheese would you think has more kinetic energy now? Yes, the heavier or more massive object, in this case, the cheddar, will have more kinetic energy. Let's make it a little more complicated. Brother and sister rat are full, so they send the cheeses back for mama rat. Brother rat pushes the larger piece of cheddar and sister rat pushes the smaller piece of Swiss so that the Swiss is going twice as fast as the cheddar. Now, which cheese has more kinetic energy? In fact, it turns out that it's the Swiss in this scenario. Kinetic energy depends on both mass and speed, but the dependence on speed is stronger. This estimation of kinetic energy can be quantified in an equation that lets us calculate kinetic energy exactly. We said kinetic energy depends on the mass and the speed, which we'll write as V for velocity, so we can start with K E equals M times V. But we said that it depends more on the speed, so the velocity here is actually squared. This means that if an object's mass doubles, its kinetic energy also doubles, but if its speed doubles, the kinetic energy actually quadruples. And there's also a constant factor of 1/2 at the beginning of the equation, but we won't go into the details of the math of deriving this today. So, this is the equation for kinetic energy, 1/2 M V squared. Let's apply this equation to our cheesy example. Say the Swiss has a mass of .05 kilograms, which makes the cheddar's mass .1 kilograms. When both cheeses have the same speed, say two meters per second, the cheddar's kinetic energy is 1/2 times .1 kilograms, times two meters per second squared, which is .2 Joules. The Swiss's kinetic energy is 1/2 times .05 kilograms times two meters per second squared, which is .1 Joules, or half the kinetic energy of the cheddar. So we can see that at the same speed, the cheddar has more kinetic energy because it has more mass. But when the Swiss has a speed of four meters per second and the cheddar still has a speed of two meters per second, the Swiss's kinetic energy is now 1/2 times .05 kilograms times four meters per second squared, which is .4 Joules. So now, the kinetic energy of the Swiss is twice the kinetic energy of the cheddar. So we can see that even though the cheddar has more mass the Swiss has more kinetic energy because it's going faster. In summary, kinetic energy is the motion energy of an object. The equation for kinetic energy is 1/2 M V squared. So as mass increases, kinetic energy increases, like the more massive cheddar versus the Swiss, and as velocity increases, kinetic energy increases even more, like the speedy Swiss versus the slower cheddar. Thanks for watching, and I hope you learned a little bit of something.