Today we're going to be continuing on our 
energy conversion. 
And we're going to dive a little deeper 
into the first law of energy conversion 
that I covered very briefly in the last 
lecture. 
And show some examples and try to get a 
little better understanding of what we're 
talking about and what the, what the 
limitations do to us regarding the first 
law of energy conversion. 
That say's you cannot create or destroy 
energy. 
and we're dealing with the middle box 
here, where we're, converting energy from 
one form that we find in it's natural 
state, to the form that society Needs and 
wants they're willing to pay for. 
We've already been over this diagram, 
looking at all the infrastructure that we 
have in order to carry out this 
conversion process. 
And repeating the 1st law, total energy 
cannot be created or destroyed, it is the 
1st law and That, that sometimes comes a 
little surprising, because a lot of times 
in the press, and the media, and the 
public, we talk about producing energy. 
but when we produce energy, we're always 
using energy on the other side somewhere. 
There's got to be an energy input before 
we can produce it from our hot air 
furnace or from our, with our automobile 
or for our wind turbine or something. 
There's got to be an energy source in 
order to produce energy. 
So we're not, we're never creating 
energy, we're only converting it again 
from one form to the other. 
So I can't say that enough. 
Now there, to dive a little deeper we 
need to understand what types and forms 
of energy we're talking about here. 
What all, are some of the different forms 
that we typically deal with. 
Well work is one of the, one of the most 
valuable forms that we have and that is, 
as an example, is a turning shaft that 
turns the axle to our car with a torque 
on it that drives our car or when we 
pedal our bicycle, we're turning a shaft 
that powers the rear wheel that pushes us 
up a hill or against the wind resistance 
as we ride our bicycle electricity is 
another form of energy. 
And there of course, that's a current and 
voltage that's carried over a wire. 
Electricity is a very nice form of 
energy. 
Because it's one that can be transported 
over long distances very efficiently. 
Work, you got to have a shaft. 
And to carry that work from one place to 
another. 
Of course, you don't want to have a mile 
off shaft to carry work from one place to 
another. 
But we can produce electricity at one 
place and carry it over a mile long power 
line. 
And then use it to power an electric 
motor on the other end. 
And that can produce our work. 
So electricity is one that. 
That is a very nice form of energy. 
But, of course, we don't find it in a 
natural state. 
We always have to generate it from some 
other source. 
Kinetic energy is one that we're 
probably, fairly familiar with in, that 
regarding a moving car. 
you have to put energy into the car from 
when you're at a stop light in order to 
accelerate it to 25 mph to get to the 
next stop light in, in traffic. 
so it has kinetic energy and then if, 
unless you're dealing with a hybrid car, 
you put your brakes on which produces 
friction and turns that kinetic energy 
into heat. 
That heats up the breaks and dissipate 
that energy, that kinetic energy. 
Dissipate it into thermal energy or into 
the atmosphere. 
So it's wasted, so to speak. 
we put it into the card to create the 
kinetic energy but then we don't get it 
back out. 
The hybrid car uses a generator to. 
link into the brakes, and the braking is 
done with a generator that generates 
electricity then and stores it in the 
battery to accelerate when we get ready 
to start back up, from the stop light. 
thermal energy is and, and that's 
sometimes we call heat. 
This one that a warm cup of coffee is 
contains thermal energy. 
Any kind of, of object that has a 
temperature above ambient temperature. 
Whatever the ambient atmospheric 
temperature is at that point in time. 
If you have any substance at a 
temperature higher than that, that's what 
we call thermal energy or heat. 
Hot air, hot coffee, or warm house 
inside. 
All that's thermal energy. 
And it's another form of energy that we 
want and like. 
Hot water to shower with is another place 
where we have thermal energy or heat, as 
sometimes we call it. 
chemical energy is one that's in the, the 
chemical make up with our, our electrons 
bonded to the other molecules into the 
nucleus of our atoms and molecules and, 
we can carry out a chemical reaction and 
release that, chemical energy, or we can 
create more chemical energy by putting 
energy into it driving the chemical 
reaction to increase the chemical energy. 
So gasoline is 1 that is an example 
there. 
Gasoline has chemical energy in it. 
And we carry out a chemical reaction of 
that gasoline with oxygen in the air. 
As we saw the formula when we Talking 
about oil and, that releases, that 
chemical energy as thermal energy, or 
heat and can, and produces a very high 
temperature flame, that when can use to 
heat homes or to heat hot water or Drive 
a power plant. 
Radiation is the final example that I 
give you and that's of course the best 
example is the sun's rays that, radiation 
coming from the sun is radiation energy. 
You also feel it in front of a fireplace, 
if you have a. 
Wood burning fireplace then, and you have 
a lot of hot coals. 
Those coals radiate that, and that's 
thermal radiation we call it. 
But the sun rays of course, that 
radiation is 1 that we use in solar 
energy to produce electricity or produce 
hot water to heat our pools and. 
The things, so those are just some of the 
forms of energy and we can convert these 
forms from one to the other, as is shown 
here. 
So we put energy into some kind of energy 
conversion system that would design to 
take that form of energy. 
Work, electricity, heat, chemical energy 
kinetic energy, potential energy, etc., 
and, and convert it to some other form of 
work, eletric, that is one of the work, 
electricity, heat, chemical, kinetic, 
potential, etc. 
for instance, you can take you can take 
work, and put it into a generator, 
electric generator and electricity comes 
out of the generator. 
So that's one of the energy conversion 
processes. 
That we do a lot in, to produce 
electricity. 
we might put heat in by burning coal in a 
power plant, and dry, and boil steam and 
go through a cycle that produces 
electricity also kinetic energy is I 
already mentioned, an automobile is one 
of the best examples of that. 
Potential energy, if the automobile is 
high on a mountain then it has potential 
energy. 
As it, and gives up that potential energy 
as it comes down the mountain or comes 
down the hill and you can Easily convert 
kinetic energy from the dropping 
potential energy as you coast down the 
hill with a bicycle or a car. 
So we got potential energy coming in on 
the left hand side and kinetic energy as 
a vehicle, or bicycles speeds up as you 
come down the hills. 
So all of these, these are energy 
conversion processes. 
Some of them are more complicated than 
others. 
Some of them are more difficult to 
execute than others. 
But they're very important to use the 
energy forms that we find available to us 
on Earth. 
To. 
produce the forms of energy that we want 
in order to make life more comfortable. 
taking an example, and I mentioned the 
bicycle coasting down a hill, That 
converts the potential energy to kinetic 
energy and I just put some numbers on 
here to show, you don't need to know how 
to make the calculations. 
Some of you probably do but just as an 
example, if you have a 10 ft high hill 
and you coast, coast down a hill this 10 
ft high and you have no wind drag or 
wheel friction, varying friction and 
rolling friction of the tire on the 
surface. 
Then you could, the vehicle, the bicycle 
would accelerate 17 miles per hour. 
And that would be true for a car as well 
as for a bicycle. 
It would be, it's irrelevant of the mass. 
in the metric system, if it's a 3 meter 
high hill And you coast down it, you'll 
can ideally create 28 kilometer per hour 
speed. 
but that's the ideal, that's the upper 
limit. 
If somebody comes to me and says he can 
do better than that, then I am very 
skeptical about something because, it, 
it's, it someway energy is being created 
from something else. 
Are created from nothing, so this is the 
upper limit if we have a friction-less 
process, ideal friction-less process with 
no wind drag and no rolling friction. 
but total energy is not created. 
Energy is merely converted from potential 
energy to kinetic in this, so this a, a 
good practical example, one that you 
could probably intuitively understand. 
But of course, we do the opposite when 
we, when we climb back up the hill. 
We're adding potential energy to 
ourselves and to the bicycle so that we 
can coast down. 
On the other side. 
Another example is we take natural gas 
chemical energy and we burn it with the 
oxygen in the air. 
Furnace is shown on the right hand side, 
that's a typical warm air furnace as we 
call it in the US. 
The European Western European and in 
other countries. 
Don't have as many of the warm air 
furnaces, they have more water radiators. 
But this one burns natural gas and 
releases a chemical energy into a flame 
and that warm thermal energy is then 
transferred to the air that's circulated 
from the house and fed, then blown with a 
fan back into the house. 
So warm air heat is added back to the air 
in the house. 
from the chemical start what, the energy 
that started off as chemical energy in 
the natural gas. 
So, the gas furnace is a nice energy 
conversion device. 
Converting chemical energy to chemical 
energy or heat. 
[SOUND] so those are some examples and 
trying to get a little better handle on 
what we mean when we talk about energy is 
conserved. 
Total energy conserved not kinetic energy 
is conserved or potential energy is 
conserved or chemical energy is 
conserved. 
But total energy of all of the those 
added together of the Earth are in our 
box that we're dealing with. 
you can't, can have more energy coming 
out than you have going in. 
Okay, thank you. 
Next time we'll deal with the second law 
in a little bit more detail. 
Thank you.