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UNIT 5 NATURAL SCIENCE: SOUND, LIGHT AND HEAT

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Subido el 27 de abril de 2020 por Natalia M.

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Hello, today we are going to learn Unit 5 from Natural Science, Heat, Light and Sound, or Sound, Light, Heat, I think that's the title in the book. 00:00:00
So we start with the first page, number one, sound. We are going to start explaining sound, is there sound in space? 00:00:13
space? Well, we know that when an object vibrates it produces sound waves. And what's that? 00:00:22
Sound waves can travel through a medium, liquids, solids and gases. So, sound waves can travel 00:00:32
through water, through a rock or through air. Nevertheless, they can't travel through a 00:00:39
vacuum, the space. No puede viajar en el vacío, por el espacio. And sound waves can also travel 00:00:47
faster through water than through air, ok? Viajan más rápido por el agua que por el 00:00:56
aire. Why? Because in water the particles are closer together, so energy vibrations 00:01:03
are passed quicker from one particle to another compared to air particles, ¿vale? Las partículas 00:01:10
of the water, they are closer together and then they pass between them much faster 00:01:16
so these are sound waves and you can find there a picture 00:01:24
number two is about light, what is a light source? 00:01:27
well, light is a form of energy that allows us to see objects 00:01:32
if there is no light we cannot see 00:01:37
so we can classify light sources into artificial 00:01:39
which means that they are man-made, such as a torch or a lamp, or natural, such as lightning 00:01:44
or the sun. We can find these light sources, natural light sources, in nature. 00:01:52
Characteristics of light. Light has three characteristics, speed, direction and color. 00:02:00
the speed well light is the fastest form of energy it travels are 300,000 00:02:07
kilometers per second which is a lot direction light travels in a straight 00:02:15
line and this is called rays los rayos del sol straight line linea recta always 00:02:21
and can't pass through all materials no puede traspasar todos los materiales so 00:02:26
according to the materials light can pass through they can be these 00:02:32
These materials can be classified into three, opaque, los opacos, do not allow any light 00:02:37
through them, no puede pasar la luz a través de ellos, por ejemplo una puerta, si una puerta 00:02:44
está cerrada la luz no puede atravesarla. 00:02:48
Translucent materials allow some light through them, materiales translúcidos, por ejemplo 00:02:52
una mampara de la ducha, si en las que tenéis en casa algunas son transparentes y otras 00:02:58
and transparent materials allow all the light through them 00:03:04
the third characteristic of light is color 00:03:22
light appears white but it's composed by the seven colors of the rainbow 00:03:26
Nos parece blanca, pero está compuesta por los siete colores del arcoíris. 00:03:34
When light touches an object, it can be absorbed, reflected or refracted. 00:03:39
¿Vale? Cuando la luz toca un objeto, esta luz puede ser absorbida, reflejada o refractada. 00:03:46
¿De acuerdo? Lo vamos a ver en la siguiente diapositiva, in the next slide. 00:03:54
Light properties, propiedades de la luz. 00:03:59
we have three, one of them is reflection, light hits an object and bounces back 00:04:02
es decir que rebota, la luz toca un objeto y rebota 00:04:09
y depende de cómo sea este objeto, este objeto puede tener una superficie smooth 00:04:12
o una superficie rough, o lisa o rugosa 00:04:17
when the surface is smooth all the rays reflect in the same way 00:04:21
me miro al espejo y ese espejo me devuelve mi imagen tal y como es 00:04:26
When the surface is rough, all the rays reflect in different directions. 00:04:30
Y significa que si la superficie es rugosa, como el ejemplo que tenéis en la pantalla, 00:04:36
esos espejos que tienen formas, ¿verdad? No son espejos totalmente rectos, son cóncavos, convexos, 00:04:41
hacen formas raras, la imagen que me devuelven no es la mía, no es la real, es una diferente a la real. 00:04:48
also we have refraction, light changes directions when it passes from one medium to another 00:04:56
for example from air to water 00:05:03
as you can see in the example we have a glass of water with a straw 00:05:05
con una pajita 00:05:09
la imagen parece que la pajita se dobla, ¿verdad? 00:05:10
y esto es porque una parte de la pajita la luz está pasando a través del aire 00:05:17
y de repente cuando toca el agua 00:05:21
es que la luz atraviesa el agua 00:05:24
con lo cual está viajando 00:05:27
la luz cambia de dirección 00:05:29
cuando pasa de viajar por el aire 00:05:31
a viajar por el agua 00:05:34
no tiene nada que ver, ¿vale? 00:05:36
se refracta 00:05:38
How are rainbows formed? 00:05:39
¿Cómo se forman los arcoiris? 00:05:43
tiene que ver con la diapositiva anterior 00:05:45
con el refraction, ¿vale? 00:05:47
Rainbows are formed through refraction 00:05:48
and you have a picture there 00:05:50
So, when I see light, light travels through air and suddenly when it rains, it touches a raindrop, una gota de lluvia, it touches a raindrop and this raindrop is made of water, so light travels from air to water, yes, and light is reflected, turning the sunlight, which is white, into the seven colors of the rainbow. 00:05:52
we also use refraction to see 00:06:17
we use glasses 00:06:21
which are carved pieces of plastic 00:06:22
or glass and mirrors 00:06:24
cuando alguien no ve bien 00:06:26
sin gafas 00:06:29
es porque tiene miopía, etc 00:06:29
bueno, pues necesito unas gafas para ver 00:06:32
estas gafas tienen 00:06:35
diferentes tipos de curvaturas 00:06:36
son curvas porque lo que hacen es que 00:06:38
funcionan como una lente 00:06:40
me acerca o me aleja los objetos 00:06:42
para que yo los pueda ver 00:06:44
apropiadamente 00:06:45
Now we are going to talk about heat. What is the difference between heat and temperature? 00:06:47
Heat is thermal energy which can travel in any direction, so heat travels in any direction, 00:06:54
any. Do you remember that before we were talking about other forms of light and sound and they 00:07:03
cannot travel in any direction they can travel in a straight line you remember 00:07:13
that but so heat can travel in any direction heat is energy and temperature 00:07:18
measures how hot or cold something is so that's the difference and heat is the 00:07:25
energy and the temperature is measures how hot or cold something is 00:07:31
para medir el calor, el calor o lo frío que hace. We have two sources of heat, natural sources such 00:07:38
as the sun or the geothermal energy and then we have other sources which are artificial such as 00:07:45
the central heating for example or gas. Properties of materials, depending on how some materials 00:07:52
transfer the heat we can classify them into two, thermal insulators or thermal conductors. 00:08:00
The thermal insulators don't transfer heat very effectively, so they are not metals, that means that if I, for example, when it's very cold, I put on a lot of clothes to cover myself, why? 00:08:07
Why? Because the clothes, the fabric, as well as the plastic and other materials that are not metals, are good insulators of heat. 00:08:24
That is, they keep me warm. The clothes keep my body warm and prevent the cold from reaching my body. 00:08:34
On the other side we have the thermal conductors. They are mainly metals and they transfer heat very effectively. 00:08:43
That's why, for example, if there is something boiling, they are cooking in the kitchen and I put a knife inside, I burn myself and the knife is like the one you see in the drawing because it is a metal and metal is a good conductor of heat. 00:08:52
However, wood is not. That's why most of the kitchen utensils are made of wood or plastic, because they are not heat conductors and they can prevent me from burning myself. 00:09:08
Effects of thermal energy. Heat can change the state of matter. So we have three kinds of changes. 00:09:23
The first one is melting, so when something is very, very, very, very cold and I heat it, it melts. 00:09:33
Evaporation, the same if I fire water and I heat water, it evaporates. 00:09:40
And then we have expansion and contraction, they are opposites. 00:09:45
Expansion is when I apply heat to one substance, it expands, such as the thermometer and the mercurial. 00:09:49
So, when I apply heat, then the mercury, what it does is that it grows 00:10:01
And the opposite, contraction is right the opposite, if it's cold, it contracts, and that's it 00:10:11
Ok, that's all, so I keep this for you in case you need any help 00:10:18
And if you need any questions, if you need to ask anything, if you have any questions, please write to me to professedincomesanoromanos.com and that's it. Bye bye. 00:10:25
Autor/es:
NATALIA MARTÍN DÍAZ
Subido por:
Natalia M.
Licencia:
Reconocimiento - No comercial
Visualizaciones:
85
Fecha:
27 de abril de 2020 - 19:53
Visibilidad:
Clave
Centro:
CP INF-PRI MESONERO ROMANOS
Duración:
10′ 39″
Relación de aspecto:
1.78:1
Resolución:
1024x576 píxeles
Tamaño:
324.44 MBytes

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