Day 4 (Jan 9) Notes Flashcards
Volume Expansion
When an object changes temperature every dimension changes not just the length
ΔV= βV ΔT
Δ V- change in volume
β=coefficient of vomme expansion
V = initial volnme
ΔT = change in temp
What is the abnormal behaviour of water?
water expands as it cools from 4° to 0°C + freezes
Why is it important?
Its essential to the survival of fish and other aquatic animals. As it cools to 4°C it sinks to the bottom taking oxygen
with it
Conduction
the movement of heat through a solid. The heat moves as the molecules collide with one another as they are vibrating. As the molecules on the outside are exposed to the heat they begin to vibrate faster and collide more forcefully with the molecules next to them. This results in heat transfer. The molecules do not move from one place to another.
Convection
Liquids and gases are fluids as their molecules can move around. Heat transfer in fluids is mostly due to a process known as convection. convection is the transfer of heat by the movement of molecules from one place to another.
ex. glass pot?
What do we know about the molecules in hot fluids compared to cold fluids?
The molecules in hot fluids are further apart making hot fluids less dense than cold fluids.
As a result, hot fluids rise and cold fluids sink. This causes convection currents.
why would the elements be placed at the bottom of a water heater?
Hot water rises which causes the water in the tank to heat quicker and more efficiently.
Radiation
the transter of energy by means of electromagnetic waves. EMR includes gamma rays, x rays, UV light, visible light, infrared light, microwaves and radio waves.
Heat radiation is the infrared portion of the spectrum.
What colour are car radiators, heat exchangers such as the coils on the back of your fridge?
The best radiators have black surfaces. they are also the best absorbers of energy
What color is the inside of a thermos? Why?
Silver. To reflect and keep the heat inside
what are some factors that affect how fast heat is transferred through an object?
-Density
-Type of material
Temperature Difference
is directly proportional to the rate of heat transfer. The greater the temperature difference the faster heat is transfered. This is why we turn down the thermostat at night.
Thickness of material (d)
The rate of heat transter is inversely proportional to the thickness of material. In other words, the thicker the material the slower the heat transfer.
