Conceptual Physics- Universal Dwelling Unit Test Flashcards
What is the formula for area (of a floor plan/living space).
length (feet or meters) x width (feet or meters) = area (square feet or square meters)
Give the total living space of a house that is 24x38 feet. Show work
24x38= 912 ft2 600+160+120+32= 912 ft2
What does a heating and cooling curve look like?
a bell shape or a upside-down hyperbola
Larger windows transfer blank heat
more
How much heat does a 5x7 window transfer compared to a 2x3 window?
5x7 35 5.8333333333…
—— = —- = ———————
2x3 6 1
The 5x7 window transfers 5.83333…. times as much as the 2x3 window
How does insulaton affect how heat is transferred
CD: air spaces- air is a bad conductor because it is a gas
CV: air spaces are too small for convection currents
Radiation: shiny or light colored surfaces reflect heat transferred by radiation.
How do you find combined R-Values
addition
Explain how you could reach R-35 using: R-10; R-5; R-7; and R-15? List 4 methods
Three layers of ten, layer of five two layers of fifteen, layer of five seven layers of five five layers of seven two layers of ten, layer of fifteen layer of fifteen, layer of ten, two layers of five
etc. anything that adds up to 35
How does heat enter leave or travel through a building?
CD: transfers heat through walls by direct contact of atoms
CV: circulates heat in house- hot air rises
R: transfers heat to outside and roof of building or through windows
Why does hot air rise? (mention Density)
Hot air is less dense than cold air. Liquids and GASES layer by density with densest objects at bottom (in this case cooler air).
What is the density formula? Provide units
grams/centimeters^3
Calculate density of cube: 6x2x9; weighs 40 grams
6x2x9= 108 (12x9 (18+90)) 108/40= 2.7g/cm^3
What is heat?
heat is the total kinetic energy in molecules
What is temperature?
measurement of average kinetic energy (how fast they are moving/speed)
Give two examples of conduction:
hand on a hot pan, molecules in a hot wall touching each other, pan being heated by stove (touching the stove)
Give two examples of convection:
wind, radiator, hot air in house,
Give two examples of radiation:
fire heating room, sun hitting the house
Two examples of Conductors:
metal; glass; solids in general
Two examples of insulators:
styrofoam (with air pockets); down; gases or pockets of gases within solids in general
Two materials that reflect heat.
aluminum, paper, white shirt
two materials that absorb heat:
dull/dark cloth; leather (not white); asphalt; black desk;
What is thermal equilibrium?
when two liquids/solids/gases of differing temperatures are in contact with each other, they with gradually become the same temp.
What direction does heat go?
from warmer to colder; except radiation, which goes in all directions
If it is: 38 degrees outside; 63 inside a gym; and a cool water bottle inside the gym is 47; then where will the heat go?
from the gym to the outside and the bottle.
How do liquids and gases layer?
from densest (at the bottom) to least dense
If something1 is 1.3 g/cm3, something2 is 3.2, and something3 is .3, how will they layer from top to bottom?
something3
something1
something2
What is the law of conservation of energy?
energy cannot be destroyed or created; it can only change form
Why does an iceberg have more heat than a pot of boiling water?
More molecules-more heat energy. Even though the temperature is less, there is more overall movement (kinetic energy) because there are so many molecules
potential energy
stored energy (stretched rubber band)
thermal energy
heat energy (fire/burning)
kinetic energy
energy of movement (released rubber band flying through air)
energy
the force that makes matter move or change; or the ability to make something move or go; many types
km
kilometer
of meters in a km
1000
cm
centimeter
of cm in a meter
100
mm
millimeter
how many mm in a meter?
1000
how many mm in a cm?
10
conduction:
heat transfer through direct contact of molecules
conductor
substance that allows heat to transfer easily
convection
heat transfer in groups of molecules; caused by differences in density; groups of molecules rise and fall due to density
radiation
heat transfer by electromagnetic waves
density
amount of matter in a unit of space; mass divided by volume; how compact something is
insulator
restricts heat transfer; a material that does not allow heat to transfer easily through it
