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Hello, guys, now we’re getting into a new topic in Physics, Thermal Physics.
Can you guess from the topic name, what this topic is about??
You guessed it! It has something to do with thermal energy! But before we get to that point, we will discuss this topic from basic to complex. (The reason for this is since I figured this is the easiest and fastest way to learn)
Molecular models of different matters in Thermal Physics
| SOLIDS | LIQUIDS | GAS |
|---|---|---|
 – Molecules are close together with regular arrangement. – Strong intermolecular forces. – Can vibrate but can’t move freely. – Cannot flow which means it has a fixed shape. |  – Molecules are close together with random arrangement. – Weaker intermolecular forces than solids. – Molecules move around. – Can flow to the shape of its container. |  – Molecules are far apart with random arrangement. – Weak intermolecular forces. – Move quickly in all directions. – Flow to fit their container. |
These features of each matter will be oftenly asked in IGCSE exams. Such as what is the difference between solid and liquid, molecularly.
You can answer: Liquid molecules can flow while solids can’t; Liquid has weaker intermolecular forces than solids; Liquids can flow while solids can only vibrate; Solid molecules are strongly attached while liquid molecules can move more freely.
As long as you remember at least 3 of each matter’s properties, you will easily ace this type of question.
—
Temperature, Pressure, and Volume
All of these factors are related to GAS. We will explore how each factor affects gas molecules.
An important theory related to gas is the Brownian motion which basically states that:
- Gas molecules move rapidly and randomly.
- They collide with each other causing the rapid speed and randomness.
- Larger particles can be moved by smaller, fast moving particles.
Let’s start with temperature.
Temperature affects the average kinetic energy (KEa) of a gas particle. This increased Kinetic energy makes the gas particles move even faster. So we know now that, the greater the KEa , the greater the average speed of the molecule.
Next, Pressure and Volume.
When a gas particle collides with a container wall, it will exert pressure. When the particle changes direction after hitting a wall, velocity will change, thus momentum will change since momentum is velocity multiplied by mass. This also means that a force will be exerted since force is momentum over time.
Another formula that would be worth remembering is for Pressure, Volume, and Temperature is:
This formula tells us a couple of things such as: If the value of temperature is constant, and the pressure increases, then the volume will decrease as a result. Just test the equation by inputting some values, you should see what I’m saying.
THAT’S ALL FOR THIS SECTION BLOG!!
You might be wondering, there’s no thermal energy at all here >:(
Welp, this is the easy section. I will provide an intermediate level blog later on that consists of thermal energy, evaporation, and others. Just let this blog sink in first.
p.s for easy revision notes on this topic, go check out: https://issr.edu.kh/science/CIE/0625%20iGCSE%20Physics/Summary%20Notes/0625%20CIE%20iGCSE%20-%202%20Thermal%20-%20Summary%20Notes.pdf
Also, if you want to check out some other physics notes, go check out https://prodatblog.org/useful-tips-for-igcse-physics-1-3/
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