Surroundable Downswell Physics: Pressure and Temperature

Introduction

• Today's lesson focuses on "Pressure and Temperature."
• Reminder to like and subscribe to the channel.

Understanding Gas Pressure

• Concept: Gas pressure is caused by particles moving in random directions and colliding with the walls of a container.
  • Pressure Formula: Pressure = Force / Area
  • Explanation: Each collision with the wall exerts a force over an area, hence exerting pressure.

Effect of Temperature on Gas Pressure

• Increasing the temperature:
  • Particles gain kinetic energy and move faster.
  • More collisions per second with walls increase the pressure.
  • Pressure is proportional to temperature (in Kelvin).
• Decreasing the temperature reduces pressure.

Graphing Pressure vs. Temperature

• Experiment: Three balloons at different temperatures: 0°C (freezer), 25°C (room temperature), and 60°C (hot room).
• Observation: Pressure increases with temperature.
• Graph Analysis:
  • Pressure vs. Temperature in °C is not directly proportional.
  • Extrapolating the line to find where pressure = 0 gives absolute zero at -273°C.

Absolute Zero and Kelvin Scale

• Absolute Zero: -273°C is the temperature at which pressure is zero; kinetic energy of particles is zero.
• Kelvin Scale Introduction:
  • 0 Kelvin = -273°C
  • Conversion: °C to Kelvin = °C + 273; Kelvin to °C = Kelvin - 273
• Graph: Pressure vs. Temperature in Kelvin is directly proportional.

Practical Calculations

• Conversions:
  • 25°C = 298K
  • 30K = -243°C
  • -5°C = 268K
  • 280K = 7°C

Key Formula

• Proportionality: P ∝ T (in Kelvin)
• Equation: P = kT (k is a constant)
• For two states, P1/T1 = P2/T2 (constant k remains the same)

Example Problem

• Scenario: Car tire pressure changes with temperature.
  • Initial pressure (P1): 6.10 x 10^10 Pascal
  • Initial temperature (T1): 280K
  • Final temperature (T2): 300K
• Calculation: Rearrange and use P1/T1 = P2/T2 to find P2
  • P2 = (P1 * T2) / T1
  • Result: P2 = 6.54 x 10^10 Pascal*

Conclusion

• Emphasized the understanding of how pressure is related to temperature, especially using the Kelvin scale.
• Reminder to like, subscribe, and practice algebra for rearranging equations.

Note:

This summary captures key points from the lecture on pressure and temperature relationships in gases, particularly focusing on how changes in temperature affect gas pressure and the concept of absolute zero and Kelvin scale.