Temperature Conversion and Thermal Energy

Study Notes

Temperature is commonly measured in Celsius (°C), Fahrenheit (°F), and Kelvin (K).
Celsius to Fahrenheit: 𝐹 = (9/5 × 𝐶) + 32.
- Example: 25°C converts to 77°F.
Fahrenheit to Celsius: 𝐶 = 5/9 × (𝐹 − 32).
- Example: 77°F converts to 25°C.
Celsius to Kelvin: 𝐾 = 𝐶 + 273.15.
- Example: 25°C converts to 298.15 K.
Kelvin to Celsius: 𝐶 = 𝐾 − 273.15.
- Example: 298.15 K converts to 25°C.
Fahrenheit to Kelvin: 𝐾 = 5/9 × (𝐹 − 32) + 273.15.

Thermal energy is the energy an object possesses due to the motion of its particles.
Particles in Solids:
- Particles are tightly packed and vibrate in place.
- Energy is mainly in the form of vibration.
Particles in Liquids:
- Particles are more spread out and move more freely than in solids.
- Energy exists in vibration and movement forms.
Particles in Gases:
- Particles are very spread out and move rapidly.
- Molecules have the most kinetic energy due to constant motion.
Adding heat to a substance causes particles to move faster and spread out, leading to expansion.
Cooling a substance causes particles to slow down and move closer, leading to contraction.

Energy transfer occurs when heat flows from one place to another.
The main mechanisms of heat transfer include conduction, convection, and radiation.
Conduction:
- Energy transfer occurs through direct contact.
- Happens in solids and liquids.
- Faster-vibrating particles transfer energy to neighboring cooler particles.
- Example: A metal spoon heats up in hot water.
Convection:
- Energy transfer occurs through fluid motion.
- Happens in liquids and gases.
- Warm fluid rises, and cooler fluid sinks, creating a current.
- Example: Warm water rises and cooler water sinks in a boiling pot.
Radiation:
- Heat transfers through electromagnetic waves.
- Can happen through a vacuum.
- Example: The Sun heats the Earth.