Physics

The Physics Philes, lesson 130: It’s Just a Phase

The Physics Philes, lesson 130: It’s Just a Phase

We’re at the end our our discussion of the thermal properties of matter. So far we’ve been talking about the simplest molecular viewpoint, ideal gases. In analyzing ideal gases, we can ignore the interactions between molecules. That certainly makes things simpler, but it’s these interactions that cause gases to condense into liquids and solids. Looking at the theoretical basis fo... »

The Physics Philes, lesson 129: Return of Heat Capacities!

The Physics Philes, lesson 129: Return of Heat Capacities!

For the past few episodes of The Physics Philes, we’ve been trying to understand the kinetic-molecular model of idea gases. Now we need to rewind a little big and go back thinking about heat capacities. Remember way back in the day we talked about molar heat capacities, or a quantity that determines the heat required for some number n of moles to change temperature. We can express this relat... »

The Physics Philes, lesson 128: Kinetic-Molecular Model of Ideal Gases, Part 3

The Physics Philes, lesson 128: Kinetic-Molecular Model of Ideal Gases, Part 3

We’ve just got a couple more topics to talk about before we can move on from the kinetic-molecular model of ideal gases. So let’s get going! First, let’s talk a little more about molecular speeds. Just to jog your memory, last week we determined the average translational kinetic energy of a gas molecule and the average kinetic translational kinetic energy per mole of gas. Those e... »

The Physics Philes, lesson 127: Kinetic-Molecular Model of Ideal Gases, Part 2

The Physics Philes, lesson 127: Kinetic-Molecular Model of Ideal Gases, Part 2

It’s been a couple of weeks, but now it’s time to continue our discussion of the kinetic-molecular model of ideal gases. Let’s have a little discussion on pressure and the kinetic energies of molecules. Let’s think about the absolute value of the velocity in the x-direction from last time. That value is not actually the same for all molecules, as you may have guessed. Howev... »

The Physics Philes, lesson 126: Kinetic-Molecular Model of Ideal Gases, Part 1

The Physics Philes, lesson 126: Kinetic-Molecular Model of Ideal Gases, Part 1

As promised, this week we’ll start a discussion on the kinetic-molecular model of ideal gases. Be warned: we’ll have to take this in chunks. Now that that’s out of the way…what is the kinetic-molecular model of idea gases? Basically, it’s a way to understand the properties of a bunch of molecules in terms of a material’s molecular structure. In this case, it mod... »

The Physics Philes, lesson 125: Timmy Fell Down the Potential Well

The Physics Philes, lesson 125: Timmy Fell Down the Potential Well

Everything we come into contact with on a regular basis – computers, door knobs, blankets, cats – are all made of molecules. Some molecules consist of only one atom, others are made up of thousands and thousands of atoms. It’s the interactions between molecules of a substance that give matter its various properties. In liquids and solids, these molecules are held together by elec... »

The Physics Philes, lesson 124: Exploding Potatoes and Equations of State

The Physics Philes, lesson 124: Exploding Potatoes and Equations of State

Last week we finished the chapter on temperature and heat. We learned what heat is, how it moves, and how its measured. It was a good time, but it’s time to move on. Now we’re going to explore the thermal properties of matter. From just living in the world, I think most of us have a fairly good understanding of heat. We know that we can turn water into steam by heating it, and we can t... »

The Physics Philes, lesson 123: Conduction, Convection, Radiation, Oh My!

The Physics Philes, lesson 123: Conduction, Convection, Radiation, Oh My!

You know, we’ve been talking a lot lately about energy transfer, aka heat. But we haven’t talked much about how that happens. Let’s fix that now. There are three ways heat can move from one place to another: conduction, convection, and radiation. First, let’s start with conduction. Say you heat one end of a metal rod. Soon, the cold part you are holding will start to heat u... »

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