In 479 BC, when Persian soldiers besieged the Greek city of Potidaea, the tide retreated much farther than usual, leaving a convenient invasion route. But this wasn't a stroke of luck. Before they had crossed halfway, the water returned in a wave higher than anyone had ever seen, drowning the attackers. The Potiidaeans believed they had been saved by the wrath of Poseidon. But what really saved them was likely the same phenomenon that has destroyed countless others a tsunami. Although tsunamis are commonly known as tidal waves, they're actually unrelated to the tidal activity caused.
By the gravitational forces of the Sun and Moon. In many ways, tsunamis are just larger versions of regular waves. They have a trough and a crest, and consist not of moving water, but the movement of energy through water. The difference is in where this energy comes from. For normal ocean waves, it comes from wind. Because this only affects the surface, the waves are limited in size and speed. But tsunamis are caused by energy originating underwater, from a volcanic eruption, a submarine landslide, or most commonly, an earthquake on the ocean floor.
Caused when the tectonic plates of the Earth's surface slip, releasing a massive amount of energy into the water. This energy travels up to the surface, displacing water and raising it above the normal sea level, but gravity pulls it back down, which makes the energy ripple outwards horizontally. Thus, the tsunami is born, moving at over 500 miles per hour. When it's far from shore, a tsunami can be barely detectable since it moves through the entire depth of the water. But when it reaches shallow water, something called wave shoaling occurs.
Because there is less water to move through, this still massive amount of energy is compressed. The wave's speed slows down, while its height rises to as much as 100 feet. The word tsunami, Japanese for harbor wave, comes from the fact that it only seems to appear near the coast. If the trough of a tsunami reaches shore first, the water will withdraw farther than normal before the wave hits, which can be misleadingly dangerous. A tsunami will not only drown people near the coast, but level buildings and trees for a mile inland or more,.
Especially in lowlying areas. As if that weren't enough, the water then retreats, dragging with it the newly created debris, and anything, or anyone, unfortunate enough to be caught in its path. The 2004 Indian Ocean tsunami was one of the deadliest natural disasters in history, killing over 200,000 people throughout South Asia. So how can we protect ourselves against this destructive force of nature People in some areas have attempted to stop tsunamis with sea walls, flood gates, and channels to divert the water. But these are not always effective.
Work as the transfer of energy
One way to find the amount of work done is by using the formula Fd cosine theta. But this number for the amount of work done represents the amount of energy transferred to an object. For instance, if you solve for the work done and you get positive 200 joules, it means that the force gave something 200 joules of energy. So if you have a way of determining the amount of energy that something gains or loses, then you have an alternate way of finding the work done, since the work done on an object is the amount of energy.
It gains or loses. For instance, imagine a 50kilogram skateboarder that starts at rest. If a force starts the skateboarder moving at 10 meters per second, that force did work on the skateboarder since it gave the skateboarder energy. The amount of kinetic energy gained by the skateboarder is 2,500 joules. That means that the work done by the force on the skateboarder was positive 2,500 joules. It's positive because the force on the skateboarder gave the skateboarder 2,500 joules. If a force gives energy to an object, then the force is doing positive work on that object.
And if a force takes away energy from an object, the force is doing negative work on that object. Now imagine that the skateboarder, who's moving with 10 meters per second, gets stopped because he crashes into a stack of bricks. The stack of bricks does negative work on the skateboarder because it takes away energy from the skateboarder. To find the work done by the stack of bricks, we just need to figure out how much energy it took away from the skateboarder. Since the skateboarder started with 2,500 joules.
Of kinetic energy and ends with zero joules of kinetic energy, it means that the work done by the bricks on the skateboarder was negative 2,500 joules. It's negative because the bricks took away energy from the skateboarder. Let's say we instead lift the bricks, which are 500 kilograms, upwards a distance of four meters. To find the work that we've done on the bricks, we could use Fd cosine theta. But we don't have to. We could just figure out the amount of energy that we've given to the bricks.
The bricks gain energy here. And they're gaining gravitational potential energy, which is given by the formula mgh. If we solve, we get that the bricks gained 19,600 joules of gravitational potential energy. That means that the work we did on the bricks was positive 19,600 joules. It's positive because our force gave the bricks energy. This idea doesn't just work with gravitational potential energy and kinetic energy. It works for every kind of energy. You can always find the work done by a force on an object if you could determine the energy that that force gives.
Einsteins Proof of Emc
In mid 1905, Albert Einstein derived what is now the most famous equation in the world E equals M C squared. But he didn't just write this down out of the blue it followed directly from his paper on special relativity that we talked about in last week's tutorial and here's how he did it Suppose you're watching a cat float freely in empty space, when suddenly it emits a flash of light in all directions. The light carries away some energy, we'll call it E , so by conservation of energy the cat must have lost energy E but since the light was emitted.
Symmetrically in all directions, it won't have changed the cat's velocity. So where did the energy for the light come from Never mind that now let's imagine you get bored and zoom off in a spaceship in the middle of the experiment. But from your new perspective, you're sitting still in your spaceship and the cat is the one moving past outside the window! Therefore you'll calculate that the cat has some kinetic energy, that is, energy of motion and when you see the cat emit the flash of light, you'll again measure that its energy decreases by the energy of the.
Light. Except now that you're moving, special relativity tells us that time passes at different rates for you and the cat, so you'll measure a different value for the frequency, and thus energy of the flash of light. This is the relativistic doppler effect, and for our purposes, it amounts to multiplying the energy of the light by one plus your velocity squared divided by twice the speed of light squared. So to recap, if you take off at velocity v, you'll see the cat gain some kinetic energy KE1, then at the flash you'll see the cat's energy decrease by E times one plus v squared.
Over two c squared. On the other hand, if you wait, you'll see the cat's energy decrease by E, and now when you take off you'll see it gain kinetic energy KE2. But this is silly! You never touch or otherwise influence the cat in either case, so you should get the same total energy at the end Rearranging, we see that the kinetic energy before and after the flash must be different! And the kinetic energy of an object is onehalf of its mass times velocity squared, but we know that the velocity was the same in both cases.
What is Solar Energy
Well there are two types of solar energy you've got solar thermal technology and you've got solar photovoltaic technology. One converts light into heat and the other converts light into electricity. Now solar thermal technology is used where it converts light into heat which you use for domestic hot water and with our systems we have developed it further where it can introduce some of that heat into your radiator system to warm your home. Solar photovoltaic technology converts light into electricity which you can use generally throughout your home for any electrical reason.
How a Prism Works to Make Rainbow Colors
Hi Folks! Here's a fun, short science tutorial showing how to use a prism to separate sunlight into a rainbow of colors. As you can see, with a little work and a sunny day you can get a pretty nice result. I bought this prism at a local store called Focus Scientific that sells telescope and other optical equipment. It's a simple five sided piece of glass with three sides forming a triangle. To demonstrate it in action I have this board on a tripod so I can arrange it any way I want. On top I've tape these two pieces of cardboard.
With a small gap between them. I start by allowing only a thin slit of sunlight to go through this gap. That's to make sure that most of the light I'm using is coming from one direction only. As you can see, even with this paper far away, this light appears white on the paper. Now I put my prism in the way of the light. You'll notice that the light no longer continues in a straight line. And it you look closely you can see all the visible colors that that sunlight is made up of.
I'll be talking only about visible light in this tutorial. Having found a good location for the prism, I tape it in place. How does it work Visible light is made up of multiple electromagnetic waves with different wavelengths. Those wavelengths represent different colors, red, orange, yellow, green, blue, indigo and violet. On this side of the prism they're all overlapping and going in the same direction. But when they cross the boundary between the air and the glass of the prism, they bend. This bending is called refraction. When they exit the prism, going from glass to air, they bend again.
The key is that the amount they bend by is different because of the different wavelengths, or colors. The result is that red light will bend something like this when entering the prism, and like this when exiting the prism. But violet light will bend something like this when entering the prism, and like this when exiting the prism. So they enter going in the same direction but leave going in different directions. And when we put this paper in the way of the light, we see the different colors separated. Putting the paper on a slant helps spread.
It across more area, so we can see the colors more clearly. And that's how a prism works to make a rainbow of colors. What if you don't have a fancy tripod or prism Get a box instead and tape some white paper to the top along with the two pieces of cardboard for the gap. Fill a plastic or glass container with water,. and use that to bend the light. It may not be as good as a prism but you'll see some color separation at the edges. Well thanks for watching!.
Rural Australia and the Renewable Energy Target
The drought, it's awe consuming. You come home and you know that you're going to have to try and sleep and get up and do it all again. We were approached to host a wind farm, we're reaping the benefits of a decision in a really tough time through the drought. If the government cut the renewable energy target, all of that opportunity has disappeared overnight, it's gone offshore. The best way to support famers is to have a stable renewable energy target that encourages investment in regional Australia. I'm not a scientist, I'm not an economist either, but it's pretty simple isn't it.
The GEN Renewable Energy For Your Home
I was tired of paying so much for electricity, so I decided to generate my own. Hi. My name is Marcio Pugina, and this is my invention the GEN. It's an electrical generator that combines wind and solar technology into one compact unit. For over 2 years, I've generated about 50 of my own electricity, and I'm working on a newer model that will generate up to 70. For a long time my wife and I wanted to produce our own electricity, but the only options available were solar panels and windmills, and they can cost up to 50,000 dollars. It.
Just didn't make financial sense. Plus, what happens when it's not windy or when it's dark We certainly didn't want to buy both. Solar panels and windmills also draw a lot of attention, and many cities and homeowner associations won't allow them. So that's when I said to myself, I'm an engineer. I'll just come up with my own invention. So after working in my garage for over a year, I came up with, the GEN. The GEN combines wind and solar technology. Since it's not always sunny, and it's not.
Always windy, this allows the GEN to produce a more consistent flow of electricity. Because the GEN is relatively small, it costs a lot less than the alternatives, it fits comfortably on your roof, much like an air conditioner, and it's more broadly accepted by cities and homeowner associations. The first month after we set it up, I got the power bill in the mail, and I was shocked. It was cut in half. I was so excited I called my husband right away. He thought I had won the lottery or something.
We are excited about the GEN, and we want to make it affordable for everyone. Our goal is to offer the improved model for 6000 dollars. Depending on where you live, you can actually get back enough tax and energy credits so that you end up paying nothing. Let's say that where you live, the GEN still costs you 3000 dollars. Compare that to the alternatives. Even after tax and energy credits, solar panels on half your roof would cost 20,000 dollars, and a windmill would cost 30,000. Now let's say you spend $150 per month on electricity. This is the average American.
Electric bill. And if you produce 50 of your own electricity, you save 75 dollars per month. At this rate, the solar panels would take approximately 22 years to pay off. With an average lifespan of 25 years, the solar panels give you only 3 years of free energy. The windmill would take about 33 years to pay off. With an average lifespan of 20 years, a windmill would never pay for itself. The GEN, on the other hand, would take only about 3 years to pay off. With an average.
Lifespan of 20 years, that gives you up to 17 years of free energy! Not only does the GEN make financial sense, it helps you become selfsufficient and better prepared in the case of a natural disaster or power outage. Plus it's safe for the environment. A lot of people have been asking me, So Marcio, when can I get one of those Well, that's where you come in. We need your help to raise $60,000 so we can begin manufacturing the GEN. The one I have on my roof has worked great so far, but it's just a prototype. The newer model is a patent.
Pending design, with additional solar panels and an improved alternator and wind turbine, and it will be manufactured here in the U.S. And it will generate as much as 70 of the electricity you need. We need a minimum of $60,000 to get started, but the fact is, the more money we raise, the more GENs we can manufacture at a lower cost, making it more affordable for everyone. So please, click the green button to donate, and help us make the GEN a reality. You'll even get a cool reward when you do.
What Is a Relay
Welcome to GTV! Today we will take a look at relays. Relays are switches that open and close circuits when actuated with an electrical signal. A switch is a device that can open and close a circuit when actuated manually, typically through a physical action by a person or an object. Relays are used in applications where it is necessary to control one or more circuits by a power signal that may or may not be isolated from the circuits being controlled and when manual actuation is not possible or practical. Here is an electrical diagram.
Of a switch. When the switch is open, the circuit is open or off. When the switch is closed, the circuit is closed or on. When a switch can be actuated with an electrical signal, the device is then typically referred to as a relay. The actuation of the relay will change the state of the contacts from open to closed or vice versus, depending on the contact configuration. Each switch in a relay is referred to as a pole. Relays may have one or more poles. The number of poles in a relay indicates the numbers of switches.
There are contained within the relay. Each pole may be configured as single or double throw, indicating the number of circuits that can be controlled per pole. Single throw means that the pole has an open state and a closed state. The relay will alternate between states when actuated. A double throw pole can control two circuits and alternate between one circuit being open while the other is closed and vice versus when actuated. A break is the number of separate places or contacts that a switch uses to open or close a single electrical.
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