Assessment Flashcards
a point when all water is evaporated from cell cavities but the cell walls are still fully saturated with moisture
Fiber Saturation Point
wood that is usually associated with high lumber strength and stiffness has a ________
high density
example of wood with high density
- kamagong
- molave
- apitong
- narra
a surface shrinkage experiences a greatest amount of movement in _________ section
tangential
the quality of wood that changes in size or in its physical property according to the direction in which it is being measured
anisotropy
theory of the physical and mechanical properties of wood and wood based materials
wood physics
a condition by which the moisture content of the wood is balanced with that of the atmospheric moisture condition
equilibrium moisture content
good indicator of the amount of wood substances in a given block of wood
density
it is a solid material from trees or shrubs
wood
the ability of wood to lose and absorb water
hygroscopicity
increased in wood dimension and volume as it gains moisture below FSP, expressed in percent
swelling
formula of %MC
%MC= (Wg- Wo/ Wo) 100
it is the increment of wood added during a single growth period
growth rings
in drying process, it is the first to be removed but the last to fill up the pores when the wood absorbs water or moisture
free water
it significantly affects the physical properties of wood as it leads to decrease in hardness and stiffness
water
the acceptable moisture levels of wood and lumber range from ___________ for interior and 9-14% for exterior
6-9%
one reason why tangential shrinkage is higher compared to radial shrinkage is because of ___________ that can limit how much wood shrinks in the radial direction
rays or wood rays
formula of longitudinal shrinkage
%LS= (Li- Lf/Li) 100
defined as the weight of the oven-dry wood divided by the weight of an equal volume of water
specific gravity
ratio of moderately high specific gravity in wood
0.601 to .700
in computing specific gravity of wood, what do we always put as a denominator
volume of wood
symbol of density
p
in determining specific gravity for a quick assessment but less accurate, what method are you going to use?
flotation method
what does density of water equivalent to pounds per cubic foot?
62.4 ft cube
what doesn’t have destructive effect on wood but more accurate and precise when it comes to determining specific gravity?
x-ray densiometry method
this principle state that a body wholly or partly submerges in a fluid experiences an upward buoyant force equal to the weight of the water displaced
Archimedes
what do we call downward force
gravitational force
defines as to keep afloat
buoy
formula of buoyant force
fb = wf- wa
what will happen if the buoyant force is less than the objects weight?
the object sinks
factors affecting buoyancy
- density of water
- volume of water displace
- local acceleration due to gravity
T/F: browne principle states that a body submerged in a fluid experiences an upward buoyant force equal to the weight of the water displaced
false - browne - ARCHIMEDES
T/F: an upward force is also called buoyancy
true
T/F: displacement happens when any object enters water
true
T/F: cork and iron has a positively buoyant while watermelon is neutrally buoyant
false - iron - WOOD
T/F: ships float in water because of the weight of the floating object (ship) that is equal to the gravitational force
false - gravitational - BUOYANT
T/F: a medium specific gravity has a ratio of .501 to .600
true
T/F: woods with lower specific gravity tend to hold paint better than those with higher specific gravity
true
T/F: density is unitless
false - density - SPECIFIC GRAVITY
T/F: the density of water with a temperature of 40C or 39F is commonly used as reference to compute SG.
false - 40 - 4C
T/F: if wood has a specific gravity of 1.00, it means its density equals that of water
true
