thermal physics

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

  Sum of all kinetic and potential energies
• How is the internal energy of a system 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 heating water after it reaches 100°C?

  It breaks bonds between water molecules
• What is the formula to calculate energy required to change temperature?

  Q = mcΔθ
• What does specific heat capacity measure?

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

  Latent heat of fusion and vaporisation
• How do you calculate the time taken for water to reach a certain temperature in a kettle?

  1. Calculate energy required using Q = mcΔθ
  2. Divide energy by power: t = Q/P
• How much energy is required to change the state of an ice cube?

  3340 J for 0.01 kg of ice
• How do you set up equations for energy transfer in a closed system with ice and water?

  Equate energy transfer in ice and water
• What is the final temperature of water after an ice cube melts?

  14.3 °C
• How do you calculate the increase in temperature of water per second?

  Δθ = Q/(mc)
• 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?

  The Kelvin scale
• What is absolute zero?

  The temperature at which particles have 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 Boyle's Law relate to gas volume and pressure?

  Increasing volume decreases pressure at constant temperature
• How can you explain gas laws using a molecular model?

  • Boyle's Law: Pressure inversely proportional to volume
  • Charles's Law: Volume directly proportional to temperature
  • Pressure Law: Pressure directly proportional to temperature
• 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?

  It is the area under the graph.

  
• What is Brownian motion?

  Random motion of larger particles in a fluid.
• What evidence did Brownian motion provide?

  Evidence for the existence of atoms and molecules.
• What does Boyle's law state about pressure and volume?

  • Pressure is inversely proportional to volume.
  • At constant temperature, increasing volume decreases pressure.
• What does Charles's law state about volume and temperature?

  • Volume is directly proportional to temperature.
  • At constant pressure, increasing temperature increases volume.
• What does the Pressure Law state?

  • Pressure is directly proportional to temperature.
  • At constant volume, increasing temperature increases pressure.
• What is the nature of the gas laws?

  They are empirical, based on observation.
• What is the kinetic theory model based on?

  It arose from theoretical assumptions.
• What are the assumptions of the kinetic theory model?

  • No intermolecular forces act on molecules.
  • Duration of collisions is negligible.
  • Molecules move randomly and collide elastically.
  • Motion follows Newton's laws.
  • Molecules move in straight lines between collisions.
• What is the change in momentum for a molecule colliding elastically?

  $2mu$
• How do you calculate the time between collisions for a molecule?

  $t =$$\frac{2l}{u}$
• How is pressure calculated from impulse and area?

  $P =$$\frac{F}{A}$