Chapter 1 – Physical Concepts
•
Standard units of measure are based on physics
1.
Numbers, Quantities, Measures, and Dimensions
o
Scientific notation – simple way to represent large and small
numbers with ease; translates any number into the product of a
coefficient multiplied by some power of 10
To multiply – add the exponents of the base 10 and multiply
the coefficients
To divide – subtract the exponents and divide the coefficients
Laws of exponents govern computation
o
Quantification yields a numerical value that reflects size or
magnitude
o
Quantities involving magnitude and direction are vectorial
quantities, vectors
o
Only magnitude – scalars
Of like dimensions can be added or subtracted directly
o
Direction must be taken into account for vectors to fully specify
the quantity
If directions differ in dimensions, vector analysis methods
must be used
o
Units of measure facilitates universal understanding
o
Dimensions of physical quantities must be considered when
combining them
o
Dimensions in mechanics and acoustics are length, time, and
mass (L, T, M)
o
Metric system is standard units of measure
L – M(eter)
M – K(ilogram)
T – s(econd)
2.
Fundamental Physical Quantities
o
Time – scalar quantity
o
Length – distance is a dimension of length and a scalar quantity
o
Displacement – when an object moves from one place to
another, vector, measured in meters
o
Mass – property of all matter; object can be weightless but
never massless; scalar, dimension M measured using a balance
in unit of grams (g)
o
Derived quantities – more complex
Area – measure in unit of cm
2
Velocity – combining dimensions of length and time, m/s,
vector
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Speed – rate at which distance is transversed, scalar
o
Velocity – time rate change in displacement, vectorial quantity
that much include direction along with magnitude
V = difference in x / difference in t
Instantaneous velocity when the difference in t = 0
o
Acceleration – instanttoinstant changes in velocity
a = difference in V / different in t
Slowing down – deceleration, denoting negative acceleration
Acceleration = 0 when velocity is constant
Vectorial quantity with units m/s
2
which signifies time rate
change of a time varying quantity
o
3 aspects of the motion of an object:
Displacement
Velocity
Acceleration
o
Force – most fundamental derived quantity, requisite to
understanding work, energy, and power
Measures of sound magnitude are related to force
3.
Force, According to Newton
o
May be defined as a push or a pull
o
3 laws of Isaac Newton; Newton’s Laws:
1 – an object at rest tends to remain at rest; an object in
motion tends to maintain its magnitude and direction of its
velocity (unless acted upon by an extraneous force)
2 – the net force acting upon an object in motion is equal to
the product of its mass and the acceleration imparted to it by
the force (in the same direction as the force)
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 Spring '11
 Durrant
 Force, Simple Harmonic Motion, Isaac Newton

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