Defintions
define thermal insulator
a substance that conducts very little thermal energy
why are metals good conductors?
metals are good conductors because they have free to move electrons that carry the current
a student heats a block of ice until it turns into liquid.
what happens?
when ice is heated its particles gain energy and start vibrating more until they break out of their fixed shape and move around each other as a liquid during melting.
what word do we use to describe the process of a solid becoming a liquid?
melting
define submlimation?
a gas changes to a solid skipping the liquid phase
are liquids good or bad conductors of heat?
most liquids are bad heat conductors.
a student puts a sealed syringe containing air into a bowl of hot water. after a few min the plunger moves outwards.
explain why?
when the syringe is heated the air particles move faster and hit the walls more often and harder. that increases the pressure inside so the gas pushes the plunger out
what do people do to prevent bridges from being destroyed in summer
people have started using rollers or gummy dividers that stretch with it
define convection current?
the transfer of thermal energy by the motion of fluid
how does convection happen in solids?
it doesn't, convection happens only in liquids and gases
who came up with brownian motion?
robert brown
state things that make particles move faster
pressure, heat/temp
define convection
convectionthe transfer of thermal energy through a material by the movement of the material itself
in what and how does conduction and convection happen?
conduction happens in metal solids and liquids because its the transfer of thermal energy by the vibrations of the particles and convection happens in liquids and gases as its the transfer of thermal energy through a looped current
a sealed can is heated, then cooled and it collapses. why?
heating turns water into steam filling the can when it cools the steam turns back into liquid reducing pressure inside. the higher outside pressure crushes the can
how does infrared radiation transfer thermal energy
they use electromagnetic waves
define electromagnetic spectrum?
a range of electromagnetic waves with different wave lenghts, which travel at the same speed and can travel through a vacuum
a hot cup of tea is poured into a metal mug.
the tea is at 80 degrees
the room is at 20 degrees
explain why metal mugs cool the tea faster than plastic mugs?
metal is a good conductor so that moves quickly from the tea through the mug. plastic is a poor conductor so heat escapes more slowly
why does a balloon shrink when put in a freezer?
the air inside the balloon cools down so the particles move slower and hit the walls less. the lower the pressure inside so the balloon shrinks
state the three states of matter
solid, liquid, gas