Physics by Walker 3rd Ed
Chapter 1: Introduction
Chapter
What is the goal of physics?
Introduction
1-1 Physics and
the Laws of
Nature
1) Physics is the study of the fundamental __________ of nature, which
underlie all physical __________________ in the universe.
1-2 Units of
Length Mass and
Time
1) Physics typically uses the _____ (two letters) unit system. In this system,
the unit of length is the __________, the unit of mass is the ___________,
and the unit of time is the __________. This system of measurement is
also known as the __________ system.
2) Most laws of physics can be written as ___________________
_______________ making it possible to make _______________ between
theoretical predictions and experimental observations.
3) As physicists make new observations, they constantly test and—if
necessary—__________ the present theories.
4) While many mathematical formulas will be encountered during this course,
it should be remembered that the entire universe can be explained using
just a __________ _________________ ideas.
2) Currently a meter is defined as the distance traveled by __________ in a
__________ in a specific amount of time. A meter is __________ feet or
about __________ percent longer than a yard.
3) A ____________ has been defined to be the mass of a particular platinumiridium alloy cylinder A quart of milk is a little less than one ____________.
4) True / False (Circle One) in physics it is acceptable to use the terms mass
and weight interchangeably.
5) A __________ is defined as the time required for a cesium-133 atom to
complete a specified number of oscillations. The most accurate clocks in
the world today are __________ clocks.
6) Complete the table of measurement units below:
Quantity
Measurement System
SI System
cgs system
British
Engineering
System
Length
Mass
Time
7) Regardless of the unit system, ____________ of the basic unit are
commonly used. Standard prefixes are used to designate common
multiples in powers of _________.
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Joseph Cox and Dan Miller
Brookwood High School
July 31, 2011
8) Common metric prefixes are shown below. The multiplier shows how
many of the _________ unit are required to equal one of the prefixed units.
9) Example Problem How many meters are in 100 km?
1-4 Significant
Figures
1) Observed values of experimental quantities have inherent
________________ created by either the limitations of the instrument or
the __________of the person using it.
2) The number of _______________ __________ in a physical quantity is
equal to the number of digits in it that are known with certainty.
3) As a rule of thumb, experimental values are assumed to have an
uncertainty of plus or minus __________ in the last significant digit. (Not in
the book. This is a very general rule of thumb. It is not at all uncommon to
encounter much higher uncertainties.)
4) Rules for determining the number of significant figures in uncertain
numbers (Not in the book.)
a) A digit is significant
i) If it is a non-__________ number.
ii) If it is the __________ digit in a number that includes a decimal
point.
iii) If it is sandwiched between two _____________ numbers.
b) To determine the number of significant figures in a number expressed
in scientific notation consider only the coefficient (the part of the
number that precedes “x 10Exponent”)
5) Example Problem Determine the number of significant digits in each of the
following numbers
a) 606 kg
b) 790 m/s
c) 26.200 m
d) 45.002 m
e) 25000 g
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Joseph Cox and Dan Miller
Brookwood High School
July 31, 2011
f)
1.09 x 1015 g
g) 300. m/s
h) 2500 x 103 kg
6) The number of significant figures after multiplication or division is equal to
the number of significant figures in the __________ accurately known
quantity.
7) Before “dropping” figures from a calculation that are insignificant, look to
see if the insignificant digits would cause the remaining significant figures
to be ____________up.
8) For the purposes of determining significant figures, ignore numbers such
as pie and conversion factors. These are considered exact and will
__________ change the overall precision of the other numbers in the
problem. (Not in the book.)
9) Example Problem Express the answer to each problem below to the proper
number of significant figures.
a) 3.0010 x 21 =
b) 2.034 x 10-21 x 500 x 105 =
c) 45.00 / 2230 =
d) 3.0 x π =
10) The number of decimal places after addition or subtraction is equal to the
_____________ number of decimal places in any of the individual terms.
This is very different from the rule for multiplication/division because it
focuses on the ____________ of the last significant figure as opposed to
just the total number of significant digits in each number
11) The best way to complete an addition or subtraction significant figure
problem is as follows: (Not in the book.)
a) Rewrite the numbers vertically and align the decimal point in each
number
b) Add or subtract the numbers as normal
c) Find the number in the calculation that had its last significant digit
farthest to the left.
d) Your answer cannot have significant figures to the right of that position.
e) Don’t forget to round up or down when you drop off the extra nonsignificant digits.
12) Special things to consider BEFORE starting a significant figure addition or
subtraction problem: (Not in the book.)
a) All numbers must have the same unit. If not, do a unit conversion first.
b) If numbers are in scientific notation, you must change them to the same
exponent before applying the rules for addition and subtraction with
significant figures.
13) Example Problem Complete the following addition or subtraction significant
problems:
a) 432.2 g + 24.06 g =
b) 324.54 km - 25.6 km =
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Joseph Cox and Dan Miller
Brookwood High School
July 31, 2011
c) 28.9 L +300.25 L + 2.945 L =
d) 12 m + 30 cm
e) 1.02 x 105 m + .02 x 107 m =
f)
3.004 x 10-6 cm +5.4 x 10-7 cm =
14) The number of significant figures in a given quantity may be ambiguous
due to the presence of _______ at the beginning or end of the number. To
remove this type of ambiguity, we can write the number in __________
_____________ — that is, as a number with the correct number of
significant figures times an appropriate power of ten.
15) Example Problem Write the following numbers in scientific notation and
express them to specified level of precision.
a) 12000 cm accurate to ± 10 cm
b) .00067 m accurate to ± .000001 m
c) 1,000,000 dollars accurate to ± 1000 dollars
d) .57 kg accurate to ± .0001 kg
16) Round-off error occurs when numerical results are rounded off at different
times during a calculation. To minimize round-off error, it's a good idea to
keep __________ extra digit throughout your calculations whenever
possible, rounding off only the __________ result. But while this practice
can help to reduce the likelihood of round-off error, there is no way to avoid
it in every situation.
Additional Practice
17) Determine the number of significant figures in each of the following
numbers:
a) 6.751
b) 28.0
c) .0067
d) 6352001
e) .157
f)
2500
g) 3400.
h) .0230
i)
2300 x 103
j)
6.67 x 10-11
18) Express each answer to the correct number of significant figures
a) 16.5 + 8 + 4.37 =
b) 2.36 + 3.38 + .355 + 1.06 =
c) 23.27 - 12.058 =
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Joseph Cox and Dan Miller
Brookwood High School
July 31, 2011
d) 350.0 - 200 =
e) 2.6 x 3.78 =
f)
3.15 x 2.5 x 4.00 =
g) .036 x .02 =
h) 40.8 / 5.050 =
i)
1-5 Converting
Units
.075 /.003 =
1) Consider the example in which 26.4 m is converted to feet
2) The numbers in the circle are known as _______________ factor. 3.28
feet is __________ to 1 m.
3) Consider the example in which 3.00 mi /h is converted to m/s
4) In each _______________ factor, the numerator is equal to the
denominator. In addition, each conversion factor is written in such a way
that the unwanted units ___________, leaving just meters per second in
the final result.
5) Conversion Factors you must know!
a) 100 cm = 1 m
b) 1000 mm = 1 m
c) 1000 g = 1 kg
d) 1 yr = 365 days
e) 1 day – 24 hours
f) 1 hour = 60 min = 3600 s
g) 1 min = 60 s
6) Remember when working with the metric system, the multiplier shows how
many of the _________ unit are required to equal one of the prefixed units.
(Section1-4)
7) Helpful Hint: When asked to go from one metric prefixed unit to another
metric prefixed unit it is often easier to go from the first prefixed unit to the
base unit and then from the base unit to the second prefixed unit.
8) Example Problem Complete the following conversions:
a) 38 cm to m
b) 38 cm to mm
c) 35 cm to nm
d) 400 mm to micrometers
e) 80 km/hr to m/s
f)
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55 mph to m/s (1 mi = 5280 feet, 3.28 ft = 1m)
Joseph Cox and Dan Miller
Brookwood High School
July 31, 2011
Additional Practice
9) Complete the following unit conversion problems
a) .75 kg to mg
b) 1.00 day to seconds
c) 3.50 m to cm
d) 65 g to kg
e) 100 m/s to km/h
f)
80 km/h to m/s
g) 55 mph to km/hr
h) 400 nm to fm
i)
1-3 Dimensional
Analysis
4.0 µC to C
1) In physics, when we speak of the ____________ of a physical quantity, we
refer to the type of quantity in question, regardless of the units used in the
measurement.
2) Any valid formula in physics must be ___________________
_______________; that is, each term in the equation must have the same
dimensions.
3) _________________ obey the same rules of algebra as other quantities.
4) A calculation done with dimensions is known as
_________________analysis.
5) When performing dimensional analysis coefficients such as ½ or 2 are
__________, but all _____________ operations are completed with the
dimensions.
6) Dimensional analysis is a powerful tool for checking the validity of formulas.
If at any time the dimensions don't agree, you will know that a
____________ has been made, and you can go back and look for it.
7) True / False (Circle One) If the dimensions on both sides of an equation
are equal you know the formula is correct.
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Joseph Cox and Dan Miller
Brookwood High School
July 31, 2011
8) Example Problem Use the table below to check the possible validity of the
physics formulas below
a) VF = VI +1/2at2
b) d = ½ (vI + vF)t
c) Energy = ½ mv3
1-7 Scalars and
Vectors
1) A _____________ is a numerical value, expressed in terms of appropriate
units. An example would be the _______________ of a room or the
__________ of a car.
2) A ____________ is a mathematical quantity with both a numerical value
and a direction. An example would be the _____________ of a car.
3) Identify each term as a vector or scalar quantity. (You might not know the
precise definition of these terms, just do your best.)
a) Time
b) Force
c) Acceleration
d) Length
e) Mass
f)
Momentum
g) Volume
h) Density
4) When working in one dimension we will use the signs ( + or -) to indicate up
or down / left or right when working with ____________ quantities.
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Joseph Cox and Dan Miller
Brookwood High School
July 31, 2011