2) Thermal Physics Flashcards
Define Brownian motion
It is the random movement of larger particles, due to their collision with faster moving, smaller particles.
Define Absolute scale of temperature
-273
Define Absolute zero
lowest theoretical temperature -273
State Boyle’s law
For a fixed mass of a gas at constant temperature, the volume varies inversely as the pressure. Hence pv=constant; where p=pressure on the gas and v=volume of the gas.
Define Thermal expansion
Thermal expansion is the expansion of an object under the influence of heat
Define Specific heat capacity
It is the amount of heat energy required to raise one kilogram (kg) of the material by one degree Celsius (°C).
Define Melting point:
t is the temperature at which a solid changes into a liquid
Define Boiling point:
It is the temperature at which a liquid changes into a gas, without a rise in temperature.
Define Evaporation:
It is the temperature at which a liquid changes into a gas, over a range of temperatures
Define Good thermal conductors
Substances that allow the heat energy to flow through them easily are called as good thermal conductors.
Define Bad thermal conductors ( good thermal insulators):
Substances that do not allow the heat energy to flow through them easily are called as good thermal insulators.
Define Conduction
Conduction is the the transfer of energy through the movement of particles that are touching each other.
Define Convection
Convection is a process of heat transfer involving density differences within molecules of the same fluid , in which the warmer and less dense portions rise up, while the more dense and the heavier ones sink down.
Define Radiation:
adiation refers to the process of transmission or emission of energy in the form of waves that can travel through vacuum, meaning they do not require any medium.
Reducing temperature
Gas molecules move slower and collide with the walls of container less and less frequently so pressure drops and volume de2creases if cooling continues molecules stop moving and occupy zero volume as no pressure exterted (absolute zero)
What happens when an object is compressd
Volume decreases pressure increases
What happens what an object expands
Volume increases pressure decreases
Pressure and Temperature (constant volume)
Increasing temerpature increases pressure as molcules increase and speed and collide with the walls of the container more often and frequently exerting a greater force.
Pressure and volume (constant termperature) vacuum pump experiment
when gas is compressed molecules will hit the walls of the conainer more frequently this creates an overall large net force which increases pressure.
Kelvin and Celcium equations
C + 273 = K
K - 273 = C
When a material is heated at constant pressure
Temp increases
volume increases (expansion)
density decreases
Why does expansion happen
Molecules start to move around or vibrate faster as they gain KE this causes them to colide with each other more often and push each other apart.
Application of thermal expanision incluse
- Liquid in gas thermometers
- Temperature activated switches
What happens if an object has low SHC or high
low = Objecat heats up and cools down quickly
High = Object heats up and cools down slowly
When substances are heated
Mass, temp = Same
Volume = increases
Density = Decreases
When substances are cooled
mass, temp = same
Volume decreases
Desnity increases
Why is black objects a better emitter and shiny objects not
black objects looses heat more quicly while shiny objects reflect heat.
