9.1 losing heat and braincells Flashcards
Heat is a?
Form of energy
Heat flows from
hotter region to colder region
What is temperature
Degree of hotness or coldness of object
how is temperature measured
thermometer
What is diff between heat and temperature
Heat:
Form of energy
Joule (J)
Depends on type + quantity of material & temperature
Temperature:
Degree of hotness / coldness of object
Celsius (`C) / Kelvin (K)
Depends on degree of movement of particles in matter
What are three forms of heat flow
Conduction
Convection
Radiation
What is conduction
Process of heat transfer from hotter -> colder region through solid
Particles that receive heat energy -> vibrate & collide with each other more frequently -> transfer heat to whole medium
What is convetion
Heat transfer by movement of fluid (liquid & gas)
What is convection current
Part of fluid that received heat -> expand & less dense -> rise
Colder & more dense fluid -> Downwards
CC = Circulating stream that rises and falls continuously
What is radiation
Process of transferring heat without medium
Heat can propogate through empty space & vacuum
What effects rate of radiation flow
Type of surface, temperature & total surface area
How does heat from Sun reach Earth
Radiation -> propagates through empty space
Penetrates atmosphere -> absorbed by water & land
What is an effect of warming of Earth by Sun
Chang in climate
Natural phenomena:
Sea breeze, land breeze, thunderstorm
Sea breeze and land breeze is an example of
natural convection process
How does sea breeze form
During day, Sun heats up land faster than sea
Warm air on land expands -> less dense -> rise bc lighter
Cold air on sea -> more dense -> draw in to replace warm air on land
How does land breeze form
At night, land cools faster than sea
Air above sea -> warmer -> less dense -> rise
Cold & more dense air from land -> move to the sea
What are heat conductors
Materials that allow heat flow
What is heat conductor in iron?
Base of iron -> metal -> conduct heat -> iron clothes quickly
What is heat conductor in bottom of a pan
Made of metal -> allow heat to flow quickly to food
What is heat conductor in theromometer
Mercury -> good heat conductor -> detect change in temp very quickly
Why isnt water used in thermometer
High adhesion force, water wont come back down
Alcohol vs mercury thermometer
Alcohol:
Non toxic - safe
Measure lower temp
Mercury:
Measure higher temp
What are heat insulators
Materials that prevent heat flow
What is heat insulator in oven gloves
Prevent hands from scald -> taking food try from oven
