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Wood Physics > Lesson 6-8 > Flashcards

Lesson 6-8 Flashcards

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1
Q

a branch of physics that studies how energy changes in a system

A

Thermodynamics

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2
Q

deals with the transfer of energy from one place to another and from one form to another

A

THERMODYNAMICS

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3
Q

a form of energy that corresponds to mechanical work

A

Heat

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4
Q

The key concept is that ____ is a form of energy corresponding to a definite amount of ______ _____.

A

heat, mechanical work

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5
Q

Four elements of fire

A

Heat, Oxygen, Fuel, Chemical Reaction

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6
Q

3 WAYS BY WHICH HEAT CAN BE TRANSFERRED

A

Conduction
Convection
Radiation

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7
Q

Heat transfers from molecule to molecule.

A

Conduction

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8
Q

Heat transfers by the movement of heated particles as in air currents.

A

Convection

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9
Q

Energy is in the form of heat or light rays is sent out from atoms and molecules as they undertake internal change.

A

Radiation

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10
Q

4 ESSENTIAL THERMAL PROPERTIES OF WOOD

A
  1. THERMAL CONDUCTIVITY
  2. HEAT CAPACITY
  3. THERMAL DIFFUSIVITY
  4. COEFFICIENT OF THERMAL EXPANSION
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11
Q

usually represented by k

A

THERMAL CONDUCTIVITY

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12
Q

measure of the rate at which heat flows through a specified material

A

THERMAL CONDUCTIVITY

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13
Q

Expressed as the amount of heat that flows per unit time through a unit area subjected to unit temperature difference

A

THERMAL CONDUCTIVITY

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14
Q

Units used to measure the heat flow or heat transfer are

A

W/(m^2/k) or W/(m^2/C)

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15
Q

amount of energy needed to raise the temperature of a specific material by 1 degree celcius

A

Heat Capacity of wood

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15
Q

factors that affect heat capacity of wood

A

temperature and moisture content

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16
Q

Measure of how fast a wood can absorb heat from its nearby environment

A

THERMAL DIFFUSIVITY OF WOOD

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16
Q

It is also defined as the ratio of thermal conductivity to the product of density and heat capacity

A

THERMAL DIFFUSIVITY OF WOOD

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17
Q

Measures the dimensional changes in wood as affected by changes in temperature.

A

COEFFICIENT OF THERMAL EXPANSION IN WOOD

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18
Q

The ovendry thermal expansion coefficients of a sample wood are ______ in all sections

A

positive

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19
Q

If the ovendry thermal expansion coefficients of a sample wood are positive the wood ________/_____ on heating and contracts on cooling.

A

wood swells or expands

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20
Q

4 ESSENTIAL THERMAL PROPERTIES OF WOOD

A
  1. THERMAL CONDUCTIVITY
  2. HEAT CAPACITY
  3. THERMAL DIFFUSIVITY
  4. COEFFICIENT OF THERMAL EXPANSION
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21
Q

Ability to absorb and prevent reflections of sound

A

Acoustic Property

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22
Q

refers to its capacity to absorb or reflect sound and reduce vibrations

A

Acoustic Property

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23
Q

If the wood has a high damping capacity, it is an ideal material for _____ _____ in which ______ __ _______.

A

structural components , vibrations is unwanted.

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23
Q

Wood is acoustic because:

A
  1. Presence of pores, vessel lines, and microcapillaries
  2. Fabricated holes
  3. Fabricated striations
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24
Q

high porosity wood is effective as a sound-absorbing material because it _____ _ ___ ___ _____.

A

exhibits a small specific impedance

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25
Q

essential in the design and construction of musical

A

Fabricated holes

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26
Q

The _____, ____, and ____ of these holes influence the ______, _____, and _____ ____ performance of the instrument

A

placement, size, and shape / resonance, tone, volume, and overall acoustic

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27
Q

It plays a significant role in determining the final sound.

A
  1. craftsmanship of the instrument
    How the wood is:
  2. treated
    3.shaped
    4.assembled
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28
Q

It has a high absorption at high frequencies; effective in reducing echoes.

A

Softwood

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28
Q

It has a moderate reflection; better for diffusing sound.

A

Softwood

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29
Q

It has a lower absorption overall; absorbs less high-frequency sound.

A

Hardwood

30
Q

It has a high reflection especially at lower
frequencies.

A

Hardwood

31
Q

The workability of this wood is more challenging, it is better at low frequencies, heavier and have lower reflection

A

Hardwood

32
Q

Unit used to measure sound, named after Alexander Graham Bell.

A

Decibel

33
Q

___-___ decibel is the normal level for human.

A

60-70

34
Q

___ __ is the maximum for safe volume level for ears.

A

80 dB

35
Q

Capacity of wood to withstand induced
vibration by sound waves transmitted
from the outside forces

A

RESONANCE OF WOOD

36
Q

Movement of electricity can be classified in two different ways

A

Direct Current (DC) and Alternating Current (AD)

37
Q

Deals with the movement or flow of energy in the form of electric charge such as electrons.

A

ELECTRICAL PROPERTIES OF WOOD

38
Q

flow of electric charge in one direction.

A

Direct Current (DC)

39
Q

flow of electric charge that frequently reverses direction.

A

Alternating Current (AD).

40
Q

DIRECT CURRENT (DC) ELECTRICAL PROPERTIES OF WOOD

A

Resistivity
Conductivity

41
Q

exhibits how strongly it resists the flow of electric current.

A

Resistivity

42
Q

as the MC of wood increases from ovendry to FSP, resistivity _______.

A

decreases

43
Q

as the MC continues to increase from FSP to complete MC saturation in wood, the _____ __ _____ _____.

A

smaller its electrical resistivity

44
Q

The higher the MC the lower the ______.

A

Resistivity

45
Q

reciprocal of electrical resistivity.

A

Conductivity

46
Q

wood’s ability to conduct electric current

A

Conductivity

47
Q

electrical conductivity of wood _____ as
temperature _____ unlike the conductivity of _____.

A

increases, increases, metal

48
Q

the wood conductivity is ___ ___ __ ____ ____ compared to the direction across the grain, and greater in the ____ ____ than in the tangential section

A

greater along the grain direction, radial section

49
Q

The AC electrical properties of wood deals with the ______ _____.

A

dielectric constant

50
Q

also known as relative permittivity

A

Dielectric Constant

51
Q

defined as the ratio of the permittivity of a substance to the permittivity of free space.

A

Dielectric Constant

52
Q

the measure of energy per unit volume stored in wood in the form of electric polarization when the material is in a given electric field.

A

dielectric constant of wood

53
Q

FACTORS AFFECTING ELECTRICAL PROPERTIES OF WOOD

A

MOISTURE CONTENT
TEMPERATURE
WOOD TYPE
GRAIN ORIENTATION

54
Q

IS A WOOD A GOOD CONDUCTOR OR INSULATOR?

A

Insulator

55
Q

What do we call the fundamental properties of wood that describes its ability to permit the transmission of an electric field?

A

Permittivity or Dielectric Constant

56
Q

Branch of science concerned with the behavior of physical bodies when subjected to forces or displacement, and the subsequent effects of the bodies on their environment

A

Mechanics

57
Q

KINDS OF STRESSES IN WOOD

A

➢COMPRESSIVE
STRESS
➢TENSILE STRESS
➢SHEAR STRESS

58
Q

A type of stress that develops when a material is subjected to an external force that tends to squeeze or shorten the wood.

A

COMPRESSIVE STRESS

59
Q

Exerted on a wood if the force tends to increase or to expand the dimension or volume of the wood.

A

TENSILE STRESS

60
Q

Relevant in situations where forces act parallel to the grain, causing adjacent layers of wood fibers to slide or deform.

A

SHEAR STRESS

61
Q

Result from forces that tends to cause portions of a wood to move or slide in parallel but opposite direction.

A

SHEAR STRESS

62
Q

Referred to as the change in length per unit of length in the direction of stress.

A

STRAIN IN WOOD

63
Q

Measure of the deformation or change in the shape of the material that results from the applied force.

A

STRAIN IN WOOD

64
Q

usually expressed in pounds per square inch (psi) or in pascals (Newton per square
meter)

A

Stress

65
Q

the pressure resulting from a force of one pound-force applied to an area of one square inch.

A

psi

66
Q

One (1) psi is equal to _____ pascals, or ____ kg/cm².

A

6,895 , 0.07

67
Q

referred to as the change in length per unit of length in the direction of stress

A

Strain

68
Q

Resistance of the wood specimen from being deformed when stress is applied

A

MODULUS OF ELASTICITY

69
Q

a longer line of MOE means it has a _____ ______ to deformity.

A

greater resistance

70
Q

TYPES OF DEFORMATION IN WOOD

A

ELASTIC DEFORMATION
TOTAL DEFORMATION

71
Q

When there is a sudden change in the shape of wood when load/stress is applied but the change is recoverable when stress is removed

A

ELASTIC DEFORMATION

72
Q

It is the line beyond the stress at proportional limit (red broken lines), where the change in size or shape of the wood when applied with stress is no longer recoverable.

A

TOTAL DEFORMATION

73
Q

Applied force

A

Stress

74
Q

Deformities

A

Strain

75
Q

the wood specimen applied with load/stress parallel to grain has the capacity to withstand the load until it reaches its breaking point

A

MODULUS OF RUPTURE

76
Q
A

Wood Physics (4 decks)

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