Thermal physics

• What is the internal energy of a body equal to?

  Sum of all kinetic and potential energies
• How can the internal energy of a system be increased?

  By doing work or increasing temperature
• What happens to internal energy when a substance changes state?

  Internal energy changes due to potential energy change
• What is the temperature of water when it starts boiling?

  100°C
• What happens to energy gained by boiling water after reaching 100°C?

  Used to break bonds, not increase temperature
• What is the formula to calculate energy required to change temperature?

  Q = mcΔθ
• What does specific heat capacity measure?

  Energy needed to raise 1 kg by 1°C
• What is the formula to calculate energy required to change state?

  Q = ml
• What is specific latent heat?

  Energy needed to change state without temperature change
• What are the two types of specific latent heat?

  Fusion and vaporisation
• How do you calculate the time taken for water to reach a certain temperature using power?

  • Use formula: \( t = \frac{Q}{P} \)
  • Where \( Q \) is energy required
  • \( P \) is power
• How much energy is required to heat 0.5 kg of water from 22°C to 100°C?

  163800 J
• How long does it take for a kettle with 1200 W power to heat water to 100°C?

  136.5 s
• What is the final temperature of water after an ice cube melts in it?

  14.3 °C
• What is the specific latent heat of fusion of ice?

  334000 J/kg
• How do you calculate the increase in temperature of water flowing past a heater?

  Use \( \Delta \theta = \frac{Q}{mc} \)
• What is the increase in temperature of water per second with a 9000 W heater?

  4.3 °C
• What do the gas laws describe?

  Relationship between pressure, volume, and temperature

  
• What is Boyle's Law?

  Pressure and volume are inversely proportional
• What is Charles' Law?

  Volume is directly proportional to absolute temperature
• What is the Pressure Law?

  Pressure is directly proportional to absolute temperature
• What is the absolute scale of temperature called?

  Kelvin scale
• What is absolute zero?

  Lowest temperature with no kinetic energy
• What is the ideal gas equation?

  pV = nRT

  
• What is molar mass?

  Mass of one mole of a substance
• How is work done on a gas calculated?

  W = pΔV
• What is Brownian motion?

  Random motion of larger particles in a fluid
• How does the molecular model explain Boyle's Law?

  • Pressure inversely proportional to volume
  • Increasing volume decreases collision frequency
  • Resulting in decreased pressure
• How does the molecular model explain Charles's Law?

  • Volume directly proportional to temperature
  • Increasing temperature increases particle energy
  • Resulting in increased volume
• How does the molecular model explain the Pressure Law?

  • Pressure directly proportional to temperature
  • Increasing temperature increases particle energy
  • Resulting in increased pressure
• What are the key concepts of the molecular kinetic theory model?

  • Particles in constant random motion
  • Collisions between particles cause pressure
  • Energy transfer occurs during collisions
• What is the specific latent heat of fusion?

  Energy needed for solid to become liquid
• What is the specific latent heat of vaporisation?

  Energy needed for liquid to become gas
• What is the relationship between Kelvin and Celsius?

  1 K change equals 1°C change
• What does the Avogadro constant represent?

  Number of atoms/molecules in one mole
• What does the Boltzmann constant relate to?

  Ideal gas equation in molecular terms
• What is the formula for work done in terms of pressure and change in volume?

  $W =$$p \Delta V$
• How is work done represented on a pressure-volume graph?

  As the area under the graph

  
• What is Brownian motion?

  Random motion of larger particles in a fluid
• What causes Brownian motion?

  Collisions with surrounding particles