Trial Prep - General questions Flashcards
What is a rapid oxidation process, which is an exothermic chemical reaction resulting in the evolution of light and heat in varying intensities
Fire
Define “fire”
A rapid oxidation process, which is an exothermic chemical reaction, resulting in the evolution of light and heat in varying intensities
Four sides of the fire tetrahedron
heat
fuel
oxidizing agent
uninhibited chemical chain reaction
oxygen % required for flaming fire
at least 14-16%
oxygen % required for smoldering fires
as little as 8%
define temperature
the degree of sensible heat of a body as measured by a thermometer
a measure of the degree of molecular activity relative to some reference point (freezing point of water)
define “heat”
a form of energy characterized by the vibration of molecules and capable of initiating and supporting chemical changes and changes of state
or. the amount of energy require to maintain or change the temperature of an object
what are the two units of heat energy?
joule
calorie (1 cal = 4 J
Define “heat transfer”
energy that is transferred between objects due to a temperature difference
which direction does heat transfer move?
from the hotter object to the colder object
Heat transfer is measured in units of what?
Watts
How many watts are in a megawatt?
1,000,000 W
Define “heat flux”
The measured rate of heat transfer to or from a defined area or surface.
does high pressure always flow to low pressure, or low to high?
high to low
what law does this represent?
PV=nRT
Ideal gas law
what is the key point to Ideal Gas Law?
If the pressure increases, then temperature increases.
if the temperature increases, then the pressure increases.
and the same if there is a drop
Name the 3 modes of heat transfer
Conduction
Convection
Radiation
What type of heat transfer involves the movement of a fluid?
convection
Which type of heat transfer is with electromagnetic waves?
radiation
which mode of heat transfer is through direct contact
conduction
Define “Thermal Conductivity”
the rate at which heat passes through a specified material
Does steel have a high or low thermal conductivity?
high
what are the two types of convection heating?
Natural (think of a car radiator and how fresh air goes across it)
Forced (heater with a mechanical fan)
How is smoke and radiation heat associated?
smoke consists of tiny, dark, solid carbon particles and each one is radiating heat.
this means, the dirtier and darker the smoke, the more radiation it will emit (high emissivity)