B1 Thermal Energy Transfers Flashcards
Explain the changes in molecular behavior during phase changes.
During phase changes (e.g., melting, boiling), molecular potential energy changes, but the random kinetic energy (temperature) remains constant.
Solve problems involving specific heat capacity and latent heat.
Specific heat capacity (Q = mcΔT), latent heat (Q = mL), where L is latent heat of fusion or vaporization.
Solve problems involving the Stefan-Boltzmann law.
Stefan-Boltzmann law relates the power radiated by a black body to its temperature (P = σAT⁴, where σ is the Stefan-Boltzmann constant).
Define density using the equation ρ = m/V.
Density (ρ) is defined as mass (m) divided by volume (V), ρ = m/V.
How do you convert between Kelvin and Celsius temperature scales?
To convert from Celsius (°C) to Kelvin (K), use the formula T(K) = t(°C) + 273.
How is the average kinetic energy of ideal gas molecules related to temperature?
The average kinetic energy of gas molecules is directly proportional to the temperature (in Kelvin) of the gas.
What is internal energy?
Internal energy is the total of intermolecular potential energy and the total random kinetic energy of molecules.
Why does temperature not change during a phase change?
During a phase change, heat energy is used to overcome intermolecular forces, causing a change in potential energy, not kinetic energy, which is why temperature remains constant.
Describe conduction, convection, and radiation as mechanisms of thermal energy transfer.
Conduction: Transfer of heat through a substance due to molecular collisions.
Convection: Heat transfer in fluids (liquids and gases) through the movement of warmer and cooler portions of the fluid.
Radiation: Transfer of heat via electromagnetic waves, without the need for a medium.
Define luminosity and apparent brightness, and solve problems involving them.
Luminosity is the total amount of energy emitted per unit time by a star or other celestial object.
Apparent brightness is the energy received per unit area at the observer’s location.
The relationship between luminosity (L), apparent brightness (b), and distance (d) is given by formula.
