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Science 4: Energy and Motion in Review 91 Views
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Description:
Unit review time! Well, geez. Don't everybody don your party hats and blow into your noisemakers at once.
Transcript
- 00:03
[Dino and Coop singing]
- 00:12
So by now, your head is probably chock-full of energy and motion facts. [Boys head opens and text books jump onto his brain]
- 00:17
In fact, it's probably getting a little hard to remember all of the facts we've crammed [Plunger cramming the books into the boys head]
- 00:21
into our brains.
- 00:22
So just in case you've lost any along the way, let's sit back, relax, and do a unit review. [Boy sat on a beach, then a laptop appears]
Full Transcript
- 00:27
…Is that not how you usually relax? [Coop appears on the laptop]
- 00:29
Well, whatever!
- 00:30
Today it is!
- 00:31
Now without further ado... [Curtains reveal 'Unit Review']
- 00:35
….the unit review!
- 00:36
We'll start with energy. [Dino pointing at a blackboard]
- 00:38
As we know, energy is the ability of an object to do work…
- 00:41
…whether that's the kinetic energy of a moving ball… [Kid running away from a big ball]
- 00:44
…the electric energy that runs through electrical wires… [Engineer up a telegraph pole]
- 00:47
…or even the nuclear energy that keeps nuclear power plants going. [A nuclear power plant]
- 00:51
And of course, these kinds of energy are very different…
- 00:53
…so you don't need to wear a hazmat suit to throw a ball around with your friends… [Two people in hazmat suits chucking a ball of toxic waste]
- 00:57
…unless you're playing a really intense game of catch….
- 01:01
One very important general form of energy is potential energy, which refers to the energy [Coop pointing at a blackboard]
- 01:05
possessed by an object.
- 01:07
There are lots of forms of potential energy, like the elastic energy stored in a bow that's [Guy pulls back a bow at an archery range]
- 01:11
drawn tight…
- 01:12
…or the chemical energy stored in all of the food we eat… [Guy eats a burger]
- 01:15
…or the gravitational energy in a roller coaster just before it's about to slide down [Roller coaster going up a steep climb]
- 01:19
and make us scream our heads off.
- 01:21
Which is one of the best kinds of potential energy.
- 01:24
Oh, and word to the wise?
- 01:25
We don't recommend mixing roller coasters with archery and eating, no matter how much [Man on a roller coaster eating a burger and using a bow]
- 01:29
potential energy gets released in the process.
- 01:31
We also learned about energy transfer, aka how different forms of energy can transform
- 01:37
into new kinds.
- 01:38
For instance, when coal is burned, chemical energy becomes heat energy… [Coal burning]
- 01:42
…which turns water into steam, making kinetic energy… [Steam appears]
- 01:45
…which moves turbines, making more kinetic energy…
- 01:48
…which turns a generator, transforming this kinetic energy into electric energy… [Sparks come from the generator]
- 01:53
…which gets sent by wires all the way to your house to produce light energy. [Person sat by a light reading a book]
- 01:58
And sure, you could just read by the light of the burning coal, but where's the fun in
- 02:02
that?
- 02:03
Another concept that came up was force: may it be with you. [Yoda next to a blackboard]
- 02:06
But outside of the Star Wars universe, force refers to a push or pull on an object.
- 02:10
This definition is pretty important in understanding Newton's three laws of motion. [Newton holding up his laws]
- 02:15
And since this is a review video, let's review what those are…
- 02:18
One: unless it's acted on by a force, an object will either not move at all…
- 02:22
…or continue moving at a constant velocity. [A wheel that is stopped and a wheel that is rolling]
- 02:25
Two: the total of all the forces on an object is equal to its mass times its acceleration. [Wheel on a scale and a car driving]
- 02:31
And last but not least, three: if one body applies a force to a second…
- 02:36
…that second body will exert a force of equal magnitude and opposite direction on
- 02:40
the first.
- 02:41
Sure, they're not as legally binding as traffic laws, but they're pretty much impossible to [Policeman stood by a stop sign]
- 02:45
break.
- 02:46
The universe is slightly more powerful than a traffic cop. [The wheel runs into the traffic cop]
- 02:49
Next on our review list?
- 02:50
The concept of friction, which is when two objects rub against each other, causing the
- 02:54
objects to slow down.
- 02:55
So when you see a ball rolling to a stop, you're not seeing some sort of miraculous [Basketball stops rolling]
- 02:59
violation of Newton's first law.
- 03:01
You're just seeing friction!
- 03:02
The rubbing of the ball against the street exerts a force in the opposite direction of
- 03:06
the ball's movement, which gradually slows the ball down. [Football slowly comes to rest]
- 03:10
Unless you're still playing with that radioactive ball….then it might just burn a hole through [The radioactive ball melts into the floor]
- 03:14
the asphalt, or something…
- 03:15
And last but not least, we also learned the difference between mass and weight.
- 03:19
An object's mass is the quantity of matter it contains… [A block is shown with mass 100kg]
- 03:22
…while its weight is the force exerted on it by gravity.
- 03:25
That means if you go somewhere with a different gravitational pull, like the moon, your mass [The block on the moon]
- 03:29
will remain the same, but your weight will change.
- 03:32
Although traveling to space might be just a little bit more pricey than a gym membership… [Woman wearing a space hat holding dumbbells]
- 03:36
Tah-dah!
- 03:37
Review completed. [Guy in a hazmat suit appears on the great wall of China]
- 03:38
Now go do something fun!
- 03:39
Play catch, or something.
- 03:40
…Man, you're really into the whole "radioactive catch" thing, aren't you…? [Radioactive balls hits the other hazmat guy and knocks him over]
- 03:44
You do you.
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