2. TOPIC OUTLINE
❑ What is physics
❑Applications of physics
❑Model
❑Physical theory
❑Physical law
❑Accuracy and precision
❑Significant figures
❑Scientific notation
❑Physical quantities and units
❑System of measurements
❑Unit conversion
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3. WHAT IS PHYSICS?
Physics is one of the most basic
sciences which deals with the
behavior and structure of matter.
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6. APPLICATIONS OF PHYSICS
▪ The laws of physics help us
understand how common
appliances work.
▪ Ex. Microwave
▪ Physics is the foundation of many
important disciplines and
contributes directly to others.
▪ Ex. Chemistry
▪ Ex. Architecture
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7. MODELS,
THEORIES,
AND LAWS
The goal of physics is to provide
understanding of the physical world by
developing theories based on experiments.
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8. MODEL
- a representation of something that is
often too difficult (or impossible) to
display directly (ex. ATOM)
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9. PHYSICAL THEORY
an explanation for patterns in nature that is
supported by scientific evidence and verified
multiple times by various groups of
researchers.
▪ detailed and can give testable predictions
▪ called physical laws when they are very
broad and well established
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10. PHYSICAL LAW
• uses concise language to describe a generalized
pattern in nature that is supported by scientific
evidence and repeated experiments.
Ex. electric charge is conserved
• often the statement takes the form of a
relationship or equation between quantities
Ex. Newton’s second law, F= ma .
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11. THEORY VS. LAW
THEORY LAW
▪ Less concise statement of
observed phenomena
▪ It explains why we observe
what we do
▪ A concise and very general
statement that describes
phenomena in nature.
▪ It describe what happens
12. ACCURACY AND PRECISION
▪ Accuracy is how close a measurement is to the correct value for that
measurement.
▪ The precision of a measurement system refers to how close the
agreement is between repeated measurements.
13. SIGNIFICANT FIGURES
❑ The measurement must be reported in a way that reflects its actual
precision.
❑ The ways to state your knowledge precisely is through the proper
use of significant figures- digits that are reliably known.
14. SIGNIFICANT FIGURES RULES
I.All non-zero numbers are significant.
36.8 has three sig figs.
II. Zeros between two non-zero numbers are significant.
2022 has four sig figs.
III. Leading zeros are not significant.
0.046 has two sig figs.
➢ Leading zeros- any zeros that come before the first non-zero number.
➢ Any zeros that come at the beginning of a number whether they’re to the
left or to the right of a decimal place or both
15. SIGNIFICANT FIGURES RULES
IV.Trailing zeros to the right of the decimal are significant.
18.00 has four sig figs.
V. Zeros appearing to the left of a decimal point, but are not followed by a
non-zero digit, are not significant.
500. has one sig fig.
VI. Zeros at the end of the whole number may or may not be significant.
1700 may be written as
1.7 x 103, 1.70 x 103, and 1.700 x 103
16. SIGNIFICANT FIGURES- ADDITION &
SUBTRACTION
The result has the same number of decimal places as the
measurement with the fewest decimal places.
17. SIGNIFICANT FIGURES- MULTIPLICATION AND
DIVISION
The result contains the same number of significant figures as the
measurement with the fewest significant figures.
18. SCIENTIFIC NOTATION
oScientific notation was invented to easily express
numbers that are too large or too small to be
conveniently written in decimal form.
oScientific notation- m x 𝟏𝟎𝐧
, where m is a number
between 1 and 10 and n is an integer (either positive
or negative)
19. SCIENTIFIC NOTATION
▪ For a number greater than 10, move the decimal point to the left until
one digit remains to its left. The remaining number is then multiplied by
10 raised to a power equal the number of spaces moved.
6 370 000 m = 6.37 x 106 m
▪ For a number less than 1, move the decimal point to the right until it
passes the first digit that isn’t a zero. The remaining number is then
multiplied by 10 to a negative power equal to the number of spaces
moved.
0.000 007 5 m = 7.5 x 10−6
m
20. PHYSICAL QUANTITIES AND UNITS
▪ Physical quantity- any number that is used to describe an observation of a
physical phenomenon.
▪ Some physical quantities are so fundamental that we can define them only by
describing a procedure for measuring them.
▪ As an example of an operational definition, we might use a ruler to measure
a length or a stopwatch to measure a time interval.
21. PHYSICAL QUANTITIES AND UNITS
▪ UNITS- are standard values used to quantify and compare
magnitudes
▪ Measurements of physical quantities are expressed in terms of
units, which are standardized values.
▪ For example, the length of a race, which is a physical quantity,
can be expressed in units of meters (for sprinters) or
kilometers (for distance runners).
22. SYSTEM OF MEASUREMENTS
1) English system- historically used in nations once ruled by the British empire and
are widely used in the United States.
2) Metric system
• units used in scientific measurements
• based on decimal system, where they are related by powers of 10.
• Ex. 1000 m = 1 km
• 100 cm = 1 m
3) International System of Units
o SI (Systeme Internationale) units are the metric units used in science and in
almost all countries outside America.
o Simplified and modernized metric system
24. FUNDAMENTAL UNITS VS. DERIVED UNITS
❑ The fundamental physical quantities are taken to be length, mass, time, and
electric charge.
❑ Derived units- algebraic combinations of length, mass, time, and current (for
example, speed is length divided by time)
Derived Quantities (based on SI units)
• Force - Newton, kg m s-2
• Pressure - Pascal, kg m-1 s-2
• Energy - Joule, kg m2 s-2
26. UNIT CONVERSION STEPS
Use the following steps to properly convert units:
1. Start with the quantity you wish to convert
2. Multiply by the appropriate conversion factor
3. Cancel out the original unit
4. Calculate the answer which should now be in the desired unit
5. Convert to the proper number of sig figs.
28. EXAMPLES OF UNIT CONVERSIONS
Convert the following to units of seconds, kilometers, and meters per
second, respectively:
1. 3.0 min
2. 60.0 mi
3. 65 mph
