Kinetic Theory And Heat Transfer and efficiency Flashcards
Describe a liquid in four points
Weak forces of attraction
Close together
Irregular arrangement
Move freely but slowly
Describe a gas in four points
Next to no forces of attraction
Far apart
Irregular arrangements
Move fast and randomly
Why do particles move faster in a substance with more heat
Because they have greater energy
Describe the basic definition of conduction
Vibrating particles passing on their excess kinetic energy to neighbouring particles
Conduction is faster in…
Dense solids
Why do dense solids increase the rate of conduction
Because the particles collide more
Insulators have….spaces between their particles
Large
Why are metals particularly good at conducting heat
Because they have delocalised electrons which collide with other electrons
Why do metals feel colder than other materials in cold weather
Because they are conducting away the heat at a faster rate
Define convection
More energetic particles move from the hotter area to the cooler area and take the energy with them
In a convection current what do the particles with the most energy do
Become less dense and rise
When the hotter particles ride what happens to the colder ones
They are displaced and therefore move downwards making them hotter and therefore less dense and heating up
Where is convection most effective
Round containers
When a gas cools down the particles…
Have less energy and move slower
The slower movement of particles leads to
The forces of attraction increasing meaning the particles get closer together and form a liquid (condense)
Describe a liquid in for points
Strong forces of attraction
Close together
Irregular arrangement
Move freely and slowly
Once the particles of a has have cooled as much a they are going to they turn into a
Liquid
What type of surface speeds up the process of condensation
A cold one
Particles in a liquid evaporate when
They are moving in the right direction and with enough force to overcome the forces of attraction
Why does evapoouration decrease the average temperature of a liquid
Because the hottest particles have escaped
What process relies on evapouration to cool in the human body
Sweating
Name four factors that increase the rate of evapouration
Higher temperature
Lower density
Greater surface area
Airflow is greater
Why does a lower density increase the rate of evapouration
Because the forces of attraction are weaker
Why does greater airflow increase the rate of evapouration
When water evaporates the air becomes a higher concentration water vapour which means less water will evaporate. Therefore if the airflow moved the concentrated air then the evapouration can continue at a faster rate
