Physics 1- (heat And Energy)) Flashcards
Unit of heat energy
Joule
Temperature is the measure of what
Average kinetic energy
The hotter something is?
The higher the average Ke
If there’s a difference in temperature between two places
Energy can flow between them
What generally happens to substances when heated
They expand
Increase in volume
Why are metals good conductors
Their electrons are free to move inside the metal
Allowing them to move KE/Heat
Why are non metals not good at conducting heat
Don’t have free electrons
Liquids conduct heat slower than what
Solids
As they have no free electrons
Why are gases very good thermal insulators
No free electrons
Particles are so far apart they don’t affect eachother
4 ways rate of conduction is affected by
Material
State of material
Surface area (larger=more collisions)
Temperature difference (bigger difference = higher rate of conduction)
The hotter an object is….
The more heat radiation it produces
For an object to stay at the same temperature
The power of heat absorbed must be equal to power of heat emitted
Dark matt surfaces absorb what
They also emit what
Heat radiation well
They emit more heat radiation
Bright glossy surfaces/silver do what?
Reflect all heat radiation on them
When does evaporation occur 2
Particles are travelling in the right direction
Travelling fast enough to overcome attractive forces of the other particles
Rate of evaporation will be faster if (3)
Temperature is higher (average KE higher)
Surface area is larger (more particles at surface edge)
Airflow over liquid is greater (lower concentration of evaporating substance in air = higher rate of evaporation. Air above the liquid is constantly being replaced keeping concentration of substance low)
Rate of condensation is affected by what (3)
Gas temperature is low (causes particles to be slow and cause clumping )
Airflow is less (concentration of substance is higher =rate of condensation higher)
Temperature of the surface of the gas is lower
Increasing surface area and volume does what to heat transfer
Increases transfer of heat (hence radiators)
Larger volumes will lose heat faster
Good conductors do what to heat transfer
Transfer heat away quicker than insulators (plastic)
Purpose of having large ears
Lose heat more quickly by radiation
Animals in desert
Density equation
Mass / volume
If the object has a lower density than the fluid
It will float
How to find the density of a irregular shaped object
Mass =scales
Volume= beaker of water. The amount the water rose by is volume
What are the stored forms of energy (3)
Chemical
Elastic potential
Gravitational potential
9 types of energy
Electrical Light Sound Kinetic Nuclear Thermal Gravitational Elastic Chemical
Efficiency =
energy out / energy in
Why are electric heaters so efficient
There’s no “waste” energy as all waste is heat which is intended use