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SECUNDARIA - 2º ESO - FORCES - PHYSICS & CHEMISTRY - FORMACIÓN

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Subido el 18 de marzo de 2020 por Cp santodomingo algete

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And now we are dealing with non-uniform movements, I mean movements which are accelerated. 00:00:01
Acceleration is the variation of velocity with times. 00:00:25
So this is the formula, the final velocity minus the initial velocity divided by the 00:00:30
time it took to change from Vf to Vo. 00:00:36
For example, if we're driving a car at, let's say, 20 kilometers per hour, and then we stop, 00:00:43
and it took us to stop two seconds, the acceleration would be 0 minus 20 divided by 2. 00:00:52
That results minus 10 kilometers per hour per second. 00:01:03
In fact, we may have positive or negative acceleration, depending on whether the final 00:01:11
velocity is bigger or smaller than the initial velocity. 00:01:19
By the way, in the international system of units, acceleration is measured in meters 00:01:27
per second squared. 00:01:35
In other words, the variation of speed in meters per second, every second. 00:01:40
The fundamental equation of dynamics was written by Newton about 400 years ago. 00:01:47
This equation establishes a direct relationship between acceleration and force. 00:01:59
But what role plays the constant m in this formula? 00:02:13
see that if m is very big then the acceleration will be small for a given 00:02:20
force. Newton called this constant m the mass, the mass of each object on which 00:02:29
the force is applied. So Newton concluded that the mass of the different 00:02:42
object is an inertial constant, as Galileo explained. You can use this web page 00:02:49
to get acquainted with this concept, force, mass and acceleration. By the way, you know that 00:03:00
acceleration is measured in meters per square second. Mass, you know, is measured in kilograms 00:03:10
and force is measured in Newton. We write this unit of force with a capital N. We can define 00:03:20
one Newton as the force required to make a mass of one kilogram accelerate one 00:03:35
meter per second squared. Then we can calculate the force required to stop 00:03:46
something in movement or conversely to speed something up. You will have to 00:03:54
perform this kind of exercise next. And so I'm also proposing you some tests 00:04:03
about these critical concepts. Mass, force and acceleration. We are dealing with the 00:04:13
classical dynamic approach. We shall learn later that Einstein was not very 00:04:23
convinced about the explanation of mass given by Newton and finally he found that mass is a kind 00:04:31
of energy or in fact mass can be converted into energy and energy can be converted into mass 00:04:41
but we cannot study this in second ESO so for the moment we shall just say that mass is a constant 00:04:49
for every object and we call it mass. It's just a constant of proportionality between the force 00:05:00
and the acceleration. That's enough for the moment. We are using Newton's equation, force 00:05:08
equals mass times the acceleration, just to solve some very simple problems in mechanics. That's all. 00:05:16
Subido por:
Cp santodomingo algete
Licencia:
Reconocimiento - Compartir igual
Visualizaciones:
292
Fecha:
18 de marzo de 2020 - 21:42
Visibilidad:
Público
Centro:
CP INF-PRI SANTO DOMINGO
Duración:
05′ 30″
Relación de aspecto:
1.78:1
Resolución:
1280x720 píxeles
Tamaño:
21.25 MBytes

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