Engineering Science N3 Heat Flashcards
What is heat?
Heat is a form of energy that flows from a hot object to a cold object.
What is the SI unit of heat?
The SI unit of heat is the Joule (J).
True or False: Heat always flows from a cold object to a hot object.
False
Define specific heat capacity.
Specific heat capacity is the amount of heat required to raise the temperature of 1 kg of a substance by 1 degree Celsius.
What is thermal conductivity?
Thermal conductivity is the property of a material that determines how well it can conduct heat.
What is conduction?
Conduction is the transfer of heat through a material without the material itself moving.
What is convection?
Convection is the transfer of heat through the movement of fluids (liquids or gases).
What is radiation?
Radiation is the transfer of heat through electromagnetic waves.
What is the formula for calculating heat energy?
Heat energy (Q) = mass (m) x specific heat capacity (c) x temperature change (ΔT)
What is the formula for calculating thermal efficiency?
Thermal efficiency = (useful output energy / input energy) x 100%
What is the zeroth law of thermodynamics?
If two systems are in thermal equilibrium with a third system, they are in thermal equilibrium with each other.
What is the first law of thermodynamics?
The first law of thermodynamics states that energy cannot be created or destroyed, only transferred or transformed.
What is the second law of thermodynamics?
The second law of thermodynamics states that heat always flows from hot to cold objects and that entropy increases over time.
What is the third law of thermodynamics?
The third law of thermodynamics states that the entropy of a perfect crystal at absolute zero is zero.
Define heat capacity.
Heat capacity is the amount of heat required to raise the temperature of an object by 1 degree Celsius.
What is the difference between heat and temperature?
Heat is the transfer of energy between objects due to a temperature difference, while temperature is a measure of the average kinetic energy of particles in a substance.
What is a heat exchanger?
A heat exchanger is a device used to transfer heat between two or more fluids.
What is the Carnot cycle?
The Carnot cycle is a theoretical thermodynamic cycle that is the most efficient cycle possible for converting heat into work.
What is the Stefan-Boltzmann law?
The Stefan-Boltzmann law states that the total energy radiated per unit surface area of a black body is proportional to the fourth power of the body’s absolute temperature.
What is the greenhouse effect?
The greenhouse effect is the process by which radiation from a planet’s atmosphere warms the planet’s surface to a temperature above what it would be without its atmosphere.
What is a heat pump?
A heat pump is a device that transfers heat from a colder area to a hotter area.
What is thermal expansion?
Thermal expansion is the tendency of matter to change in volume in response to a change in temperature.
What is the ideal gas law?
The ideal gas law is the equation of state of a hypothetical ideal gas, PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is temperature.
What is a heat sink?
A heat sink is a passive heat exchanger that transfers the heat generated by an electronic or mechanical device to a fluid medium.
What is the principle of conservation of energy?
The principle of conservation of energy states that energy cannot be created or destroyed, only converted from one form to another.
What is the conservation of energy
