transfer of hear energy and its effects Flashcards
what is the SI unit for temperature
K(kelvin)
Temperature changes occurs when heat energy is transferred from
a region of higher temperature to a region of lower temperature
heat energy=
thermal energy
effects of heat
expansion and contraction
When an object is heated, its _________ remains the same
mass
When an object is heated, its _________ increases
volume
Therefore, when an object is heated, its _________ decreases
density
because density=mass/volume,
less density=same mass/more volume
heated air ______
rises because less dense than surrounding air
example of hot air rises
hot air balloon
how is heat transferred
- Conduction
- Convection
- Radiation
what is convection
the transfer of heat through fluid(liquid/gas) caused by the molecule motion
what is conduction
the transfer of heat or electrical current from one substance to another through physical contact
what is radiation
energy that is radiated or transmitted in the form of rays, waves or particles
How do particles (atoms and molecules) transfer energy to each other?
- Collisions
- One molecule collides with another molecule and passes on kinetic energy
- Molecule with greater KE passes energy to the molecule with less KE
sort the states of matter in increasing order based on which one expands the most when subjected to the same change in thermal energy?
gas>liquid>solid
why conduction and convection of thermal energy from the sun cannot take place in outer space?
- Space is a vacuum
- There are no particles for conduction and convection to take place
how does sea breeze work/happen
In the daytime, the land heats up faster than the sea. Warm air above the land becomes less dense and rises.
Cool air above the sea which is denser moves towards the land. This sets up a convection current known as the sea breeze.
describe, using particles, how heat is transferred in metal pipes by conduction
when the pipe is heated, particles will gain more energy and vibrate more. These particles bump/collide into nearby particles and transfer some of their energy to them. this continues from the hot end down to the colder end of the object
what is the application of bimetallic strips
- fire alarms(old school)
- oven alarm
what are the 2 bimetallic strip materials that go together
- brass and steel
- copper and iron
how does a bimetallic strip work (in a fire alarm)
when the bimetallic strip is heated, it would bend more towards the side of the steel/iron. the bimetallic strip would touch the electrical wire and complete the electric circuit. this would cause the fire alarm to ring.
what material is worse radiator of heat
- white
- smooth
- shiny
how to make bimetallic strip go back to original shape
let it cool down
what material is better radiator of heat
- black
- matte
- rough
why hot air rise
gain heat, less dense & rise.
how is heat transferred in metal pipes by conduction
- conduction occurs when a sustance is heated, particles will gain more energy, and vibrate more.
- these particles then bump into nearby particles and transfer someof their energy to them, this continues from the hot end down to the colder end of the substance.
