Module 2: Physical Properties of Common Agricultural Products Flashcards
any substance or moisture or mixture of substances that occupy a volume, and has a mass
material
properties of a material
- appearance
- behavior
- name
- structure
- color
- order
- order
- composition
- any info about subtance
why is it important to study materials?
- to identify its amount and composition
- study how it will behave under a set of circumstances
- characterize, recognize, manage, and utilize materials
market value of rice is significantly affected by what?
percentage of head rice grains
what factors influence the degree of damage incurred during grain processing?
physical and mechanical properties of the material
density and specific gravity are examples of which property of material?
physical characteristics
physical characteristics - enumerate
- size and shape
- density and specific gravity
- volume
- surface area
- porosity
it deals with the characteristics of light reflected from or transmitted through an object as affected by the diff constituents of the object
optical properties
imaging used to observe optical properties
- RGB image
- near infrared (NIR) imagery
- normalized difference vegetation index (NDVI)
concerned with the strength or resistance of a particular crop when placed under stress
mechanical properties
this determines the type and severity of damage a crop will sustain and therefore dictates how that crop should be handled and processed
the resistance of a crop to mechanical stress
describe the movement of heat into or out of a material and how much it can sustain
thermal properties
thermal properties - enumerate
- thermal conductivity
- specific heat
- emissivity
- thermal capacity
- surface conductance
- transmissivity
- thermal diffusivity
- absorptivity
concerned with changes in sound transmitted through the material
acoustic properties
changes in acoustic properties may be due _____________ changes in the crop or presence of __________ damage that affect the characteristics of sound waves as they pass through the material
physiological; physical
changes in the transmittance of electromagnetic radiation, radio frequency and electrical energy
electrical properties
electrical property can be measured as crops undergo changes during _________ (maturation/ripening), go through stress conditions, or as moisture is _________ (induced, removed) from the material
maturation; removed
electrical properties
- conductance
- capacitance
- dielectric properties
- reaction to electromagnetic radiation
- conductivity-ability of seeds to hold a surface charge
physical properties of common grain crops
- grain dimensions
- volume and surface area
- density and porosity
- angle of friction
- angle of repose
what are parameters measured in grain dimensions?
- length
- width
- thickness
- diameter
physical property
basis for machine design, particle separation using sieves and grading
grain dimensions
physical property
affect rates of heat and mass transfer of a material
volume and surface area
physical property
can be estimated through resemblance to known geometric bodies such as spheres, cylinders, or ellipsoids, or by correlation with major dimensions
volume and surface area
physical property
calculation of the dimension of bulk storage facilities and intermediate holding bins of given capacity
density and porosity
density and porosity indicates the __________ degree of the grains
purity
aside from volume and surface area, which physical propertie/s are also necessary for studies on heat and mass transfer?
density and porosity
measures mass per unit volume, where volume includes pore spaces
bulk density
bulk density is dependent on
- grain moisture content
- foreign matter present
- variety of grain sample
this is measured using the water displacement method
true or particle density
measurement of mass/volume
true or particle density
true or particle density is dependent on
- grain moisture content
- variety of grain sample
gives the proportion of void space between individual grains and the volume of bulk material
porosity
maximum angle at which the grain remains in equilibrium on an inclined surface
angle of friction
angle of friction is dependent on grain moisture content, volume and type of surface
true or false
false; not volume
inclination of hoppers
φf + 10 degree
force acting in the opposite direction of movement between two surfaces sliding against one another
friction
defined as the ratio of friction force between two materials and the force keeping them in contact
coefficient of friction
refers to the angle formed by the slope of a naturally poured amount of material with the horizontal
angle of repose
angle of repose is dependent on grain moisture and?
foreign matter
knowing the properties of the material help us to develop the ability not only to identify but also to determine the amount and composition of a material
true or false
true
importance of knowing properties of a material
- market value of rice is signi affected by % of head rice grains; broken rice is less valuable than head rice
- new varieties of grains are continually being developed; their properties must be determined to assess their suitability for mechanized handling and processing
- degree of dmg due to grain processing is a function of physical and mechanical properties of the material
rice varieties can classified to dimensions of individual grains, which are
short
medium
long
long slender
medium slender
what can be used to measure grain dimensions?
vernier calipers or micrometers
combinations of size parameters such as minimum and maximum diameters, length, area, and perimeter
shape descriptors
ratio of mass of a body to its volume
specific gravity
can be determined by getting the weight of a grain sample that occupies a known volume
bulk density
for determining true density, __________ is used instead of water to minimize absorption by the grain
toluene (C7H8)
there is a positive linear connection between length, width, thickness, and equiv diameter as __________ increased
moisture content