Heat Review Flashcards
Define the four heat transfers and provide an example of each
Conduction is the transfer of heat through direct contact, like when a metal stick is heated by the flames it’s touching.
Convection is the transfer of heat through movement of a fluid, like when hot air rises off a fire and cold air sinks to the flames
Radiation is the transfer of heat through a vaccuum, like heat spreading through the air to warm someone by the fire.
Evaporation is the phase change of liquid to gas, like when a puddle slowly dissapears under the sun.
What parts constitue the core and the periphery
Brain, organs.
Arms, nose and legs, extremeties.
Provide 3 main things you can do to prevent or slow hypothermia
Reduce heat loss, add heat, and add fuels and fluids.
What are 4 ways to reduce heat loss
Get out of the way of the wind to reduce heat loss due to convection, prevent radiation of heat with jackets, try not to sweat or wear wet clothes to prevent evaporation and don’t touch anything cold to prevent conduction.
Styrofoam and thermal underwear common heat transfer trait and how does it affect
Styrofoam and thermal underwear have air pockets in the material, and air is a bad conductor of heat which makes it a good insulator
Thermos bottle features to reduce heat transfer
The bottle is reflective to prevent radiation of heat, and the layer of vaccuum space between the outer layer and the inner layer prevents conduction. The stopper’s cup enables drinking while the bottle is still closed, this prevents the hot air from rising out and losing heat (convection).
What must be present in order for a conductor to conduct heat
There has to be a difference in temperature for the conudctor to transfer heat to another ‘point’.
Two examples of good conductors and good insulators each
Aluminum and copper are good conductors, styrofoam and fiberglass are good insulators.
do some temperature conversions
What did we larn from the Good Sock, Heat Energy and Wind Chill labs
Good Sock: dry cotton decreases conductive heat loss and foil decreases radiative heat loss. Wet material increases evaporative heat loss.
Wind Chill: Wind cools hot objects, not the air itself, by carrying away the heat. Therefore wind increases radiative cooling.
Heat Energy: Microwaving is most efficient for popcorn, it’s a closed container with radiation
What does r-value tell us about insulation
The heat flow resistance capacity, the higher it is the better the insulator is.
how does popcorn pop
As the kernel heats up, the water under the surface of the starch layer expands until it explodes, causing it to pop.
why did the bimetallic strip used in the demo curve the way it did when heated
It’s two different metals welded together and they expand by different amountsm, so the metal that expands faster will bend over the slower one.
how does thermal energy always want to flow
From hot to cold
three levels of hypothermia, temps for each and 2 symptoms each
Mild, 98F-96F: Shivering and complex motor skills are difficult.
Moderate, 95-93F: Slurred speech and loss of fire motor skills.
Severe, 92-86F: Shivering in waves and can’t walk.
