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Finding the formula with experimental data - Contenido educativo

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Subido el 30 de septiembre de 2020 por Juan C. F.

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In this video, I'm going to revise what we have done today in class. 00:00:00
I'm going to teach you how to find the equation for a certain law, 00:00:04
starting with a table of data, like the ones that you have found for the period and the length. 00:00:10
Thanks to Javier Pinel, who provided with this data, that are very good. 00:00:16
And this is where we need to start. 00:00:20
I also will need a calculator, here I have one, 00:00:22
and a ruler to make the graph as good or as nice as possible so I'm going to 00:00:26
start by making the graph okay so I'm going to put like the ruler here this is 00:00:32
going to be sorry about that okay this is going to be the x-axis I use the 00:00:40
ruler now I'm going to use it again to write or to create to draw the vertical 00:00:51
axis okay so these are the vertical and the horizontal axis that we need or 00:00:57
we also need always need in the graph next I'm going to write the length in 00:01:11
the horizontal axis and I need to remember this of the length is going to 00:01:16
be here okay and the period that is symbolized by a capital T is going to be 00:01:22
on the vertical axis this is the period is measured in seconds I need to choose 00:01:30
the scales I'm going to start here for example is going to be I'm not don't 00:01:36
need to start with zeros I'm going to start with 0.7 meters here this is going 00:01:40
to be 0.8 0.9 and finally one meter okay this is this is the information that is 00:01:46
provided here in the first column of the table. Then in the vertical axis I'm 00:02:00
going to represent the period. Starting, for example, I'm going to start here like 00:02:04
this is 1.9. Notice that it's not necessary that I start in the 0, 0. I can 00:02:08
start or my origin can be other point. The important thing is to use as much of 00:02:16
the space as I can. Then this is 1 and let's say this is going to be 2, 2, 1, yes. 00:02:22
and do like this is 2.0 2.1 2.2 2.3 and sorry this is for 2.2 again 2.2 is 2.3 00:02:30
and it's a little bit and this is 2.4 I'm going to take this out I want to 00:03:04
make it nice okay so this is going to be two point four seconds seconds and I 00:03:13
remember the period is here and now I need to plot the points of the table so 00:03:20
zero point seven corresponds to a period of one point and almost two so she's 00:03:26
zero point seven is here almost two it must be around here okay this is my 00:03:33
first point of the graph, my first plot of the graph. Next is 0.8, 8 is 2.1 and a 00:03:38
quarter. So this is 0.8, 2.1 and a quarter must be around here. So this is my 00:03:45
second point 0.9 match with 2.25 2.25 2.2 25 is exactly this line between 2.2 and 00:03:55
2.3 and finally 1.0 matches 2.372 that is more or less here between 2.5 and 00:04:12
and 2.4 as you can see the points are almost in a straight line particularly 00:04:25
this they are in a straight line okay we can see this okay it's a very good set 00:04:36
of data so we can even write this draw a straight line but I want to make it nice 00:04:42
and I don't know how it doesn't work okay so we have kind of a straight line 00:04:56
and now as it is a straight line we can say that the period and the length is 00:05:09
proportional so we can say that our law has going to be a formula like this the 00:05:14
period is proportional to the length and what you need to do is to find which 00:05:20
number is this constant this K is called the slope the bigger the slope the more 00:05:28
inclined is the is a straight line to find the decay to find the constant we 00:05:36
have to work out this kind of equation if we I'm going to take this out I don't 00:05:44
need it anymore so to find K if you work out this 00:05:48
equation you will see that the constant K is the period divided by the length so 00:05:56
we are going to go to this table and in this table using the same I'm going to 00:06:07
write the constant for each pair of values I'm going to start for example 00:06:11
with 0.7 and 1.985 so I go to my calculator and the constant is 1 point 00:06:15
sorry I had to change the version the constant is one one point nine eight 00:06:23
five divided by zero point seven so this is my first value of the constant I'm 00:06:36
going to write I have four the same three decimals here four figures I have 00:06:45
one here. I'm going to set it in the middle. I'm going to use three. 00:06:50
For this set of values 2.84. The constant has units as the 00:06:57
period is seconds and the length is meters. This is seconds times meters. So we can 00:07:09
write the units of the constant as seconds times meters. We can do the same 00:07:14
with the next pair of values, I mean, 2.125 divided by 0.8 and you can see that the constant 00:07:20
is not exactly the same but it's quite similar so 2.65 and the units are the 00:07:50
same okay let's find the third value for the constant we divide zero sorry two 00:08:01
point two point two five zero we divide this by zero point nine this number 00:08:12
divided by this number okay and again the constant is not exactly the same but 00:08:25
it's quite similar 2.50 and seconds per meter and to put this properly and I 00:08:33
only have now one set one pair of values a length of one meter and this is very 00:08:46
easy so the constant is 2.37 seconds per meter so these are the four values of the constant 00:08:52
what is the real value for the constant we are going to do the average the average constant 00:09:02
i'm going to do in a different color the average constant in spanish la media we calculate by 00:09:14
By adding these four numbers, 2.84 plus 2.65 plus 2.50 and 2.37, 00:09:26
another these numbers, divided by 4, because I have four total numbers. 00:09:52
Ok, so we need to use our calculator now to do this, so is 2.84 plus 2.65 plus 2.50 plus 00:09:58
two sorry plus two point thirty point thirty seven and we divide this number 00:10:20
by four ten point this calculator works in a funny way so two point five nine two 00:10:47
comma five nine is the average value of the constant. We will accept that as the 00:11:00
real value. Don't forget the units. The units, remember, were seconds over meter. 00:11:08
Okay? So now we can write the final equation for our experiment. The period 00:11:17
is proportional to the length and the proportional constant the K is 2.54 okay 00:11:23
this would be like our final result for our experiment I hope it helps remember 00:11:35
you have to do the activity about the number of batteries and the intensity of 00:11:45
of the electric current in a circuit okay class see you next day 00:11:50
Idioma/s:
en
Autor/es:
Juan Carlos Fajardo
Subido por:
Juan C. F.
Licencia:
Reconocimiento - Compartir igual
Visualizaciones:
119
Fecha:
30 de septiembre de 2020 - 20:24
Visibilidad:
Público
Centro:
IES CLARA CAMPOAMOR
Duración:
11′ 57″
Relación de aspecto:
1.91:1
Resolución:
1024x536 píxeles
Tamaño:
29.81 MBytes

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