“I’m too cold. Get me a sweater!”
“This soup’s too hot!”
“Phew, I’m sweating.”
“Yowtch, that pan handle burned me!”
If you’ve ever made any of the above comments, then you were talking about thermal energy. Very clever of you, don’t you think? Thermal energy is basically the energy of the molecules moving inside something. The faster the molecules are moving, the more thermal energy that something has. The slower they are moving, the less thermal energy that something has.
I’m sure at some point you’ve said, “Wow, my internal thermal energy is way high! I need a liquid with a low thermal energy.” What…you’ve never said that?! Oh, wait. I bet it sounded like this when you said it, “Wow, I’m hot! I need a cool drink.” Whenever we talk about the temperature of something we are talking about its thermal energy. Let’s get started by watching this video:
Yes, and some scientist will tell you there are not 5 but 18! 🙂 We just talk about the ones you have experience with everyday, so that would be 4: solid, liquid, gas, and plasma.
arnt there five states of matter BEC, solid, liquid, gas, and plasma?
So glad you are enjoying the content! Kelvin scales (and Rankine, which is the absolute scale for Fahrenheit) are used mostly by scientists and engineers when they are doing their analysis.
For example, if I were to calculate (using math) how much heat is lost from my warm spaceship to the cold outer space, there’s a part of the equation where I need to take temperature to the fourth power (multiply temperature by itself four times, or T^4 which is TxTxTxT). Now if I do this in Celsius, I am going to get a significantly different number than if I do this in Kelvin. Can you see how 10x10x10x10 is a different number than 283x283x283x283? NASA actually made this mistake once and seriously underestimated the insulation needed to wrap the pipes in that carried liquid oxygen to the space shuttle. The results were disastrous!
All math equations must be done in absolute scales, and scientists use math to model the things they are studying. I’ve never used a Kelvin thermometer – I just add 273.15 to the Celsius thermometer. But most digital ones today will have a Kelvin scale built right in.
Aurora,
Where can we find a Kelvin thermometer? What would we use the Kelvin scale for in everyday use?
Thank you so much for this wonderful program, it has really been a treat for us to learn together as a family!
The Durham’s
Thanks Aurora!!!
That’s a great question…one I’ve wondered about also. The answer to an “absolute hot” is yes, not, and maybe. I found a really great article about it here. There are formulas for converting between the temperature scales (I think it’s in the reading section), or you can use the online converter here. Note: the article referenced above was written by Nova and is from an evolution standpoint.
HI Aurora,
This sounds like a silly question but I was just wondering what the hottest temperature you can get is, it’s probably measured on the Kelvin scale, but I’ not sure.
And what is the hottest the Kelvin scale can get to? And what’s is it equal to in Fahrenheit?
Is there a degree of heat that you just can’t get any higher, kind of like absolute zero?
Oh, one more thing, How do you convert Celsius to Kelvin? Or Fahrenheit to Kelvin?
Thanks for the help,
Rian
Thanks. That helps clarify things!
Yes, you are correct. Technically, thermal energy is the total energy of all the random motion of the molecules and atoms. The greater the kinetic energy of the particles in the substance (the more they move and jiggle around, which is another way of saying the higher the temperature), the more thermal energy the substance has. Thermal energy also depends on the number of particles in a substance, so the more particles a substance contains, the greater its thermal energy.
The temperature of the object is a measured average intensity of its thermal energy, and is independent of how many particles a substance has. The thermal energy of an object consists of the total kinetic energy of all its atoms and molecules.
Thermal energy is the total kinetic energy of atoms in a substance. Temperature is the measure of the average kinetic energy of the atoms in a substance. Does that help?
Yes, that helps. But we felt the term “amount of ” was the erroneous part. It seems temperature must be measuring an average because it is independent of the amount of substance you are measuring while “amount of thermal energy” would depend on the amount of substance you were measuring. For example, the temperature of a glass of water may be the same as that of the ocean, but the amount of thermal energy in each is very different. Is this correct?
Great job paying attention! And – we’re both right – here’s how: the temperature you read on a thermometer measures the thermal energy held inside the stuff you’re measuring (for example, a cup of water), which is ALSO known as the kinetic energy of all the microscopic random motion of the molecules and atoms inside your cup. So in this case, they are the same thing.
The term ‘kinetic energy’ is a more general term, which can also mean the energy associated with speed (as in Unit 5) of a macroscopic system like a roller coaster. You need to pay attention to the kind of kinetic energy you’re talking about when discussing KE. Does that help?
Aurora,
At one point in the video, you say temperature measures “the amount of thermal energy”. We believe you meant to say the average kinetic energy as you have in other places.
paying attention in Florida,
The Johnson’s