AP Physics 1 - Introduction

Objectives
The student will be able to:
• Identify activities in fields that involve the major areas
within physics.
• Identify the basic dimensions and their standard unit and
know how to convert between units.

The Main Areas of Physics
Physics can be broken down into seven main categories:
Name The study of...
Mechanics motion and its causes
Thermodynamics heat and temperature
Vibrations and Waves specific types of repetitive motions
Optics Light
Electromagnetism electricity, magnetism, and light
Relativity particles moving at any speed, relative to an
observer
Quantum Mechanics behavior of particles like protons, neutrons,
electrons, and even smaller things

Which area of physics would be the most
relevant to each of these situations?
o A high school football game
o Food preparation for the prom
o Playing in the school band
o Lightning in a thunderstorm
o Wearing a pair of sunglasses outside in the sun

Simplifying the Physical World
a
a
First identify the system you are attempting to study
System - set of items or interactions considered a distinct
physical entity for the purpose of study
Next, disregard all characteristics of the system that have little
to no effect on its motion.
At this point, we have constructed a model for our situation.
Model - a replica or description designed to show the structure
or workings of an object, system, or concept

What’s relevant if we want to study the ball’s motion?

Numbers as Measurements
• Numbers in math class can stand by themselves and be
meaningful
• In science, we need to give that number a dimension, or a
kind of physical measurement, in order to make it
meaningful.
• Three most common types of dimensions: length, mass,
time

SI Prefixes
The most common SI prefixes that we will use in this class are
listed below. You are responsible for memorizing these SI
prefixes.
Power Prefix Abbreviation
10-6 micro μ (pronounced mu)
10-3 milli m
10-2 centi c
103 kilo k

Converting Units
Steps for unit conversion:
1. Identify and write what you are converting from and what
unit you want to convert to.
2. Next, identify whether you have the information to convert
the unit.
3. If so, multiply the original unit by a conversion ratio.
4. Cancel units.
5. Multiply the numbers.
Sig Figs are NOT taken into account when completing a unit
conversion.

Both Dimension and Units Must Agree!
• You cannot convert
from one type of unit
to another
• ex: mass to length
• Examples of
acceptable unit
conversions
• meters to miles
• seconds to hours
• If you are measuring a length, make sure your units are in
meters

Wrap Up
• What are the three basic dimensions, what units are most
commonly used to describe them?
• A typical radio wave has a period of 1 μs. Express this time
in seconds.

Objectives
• Distinguish between accuracy and precision
• Use significant figures in measurements and calculations

Accuracy and Precision
• Careful measurements are important in science
• No measurement is perfect
• Two terms that describe this imperfection:
• Accuracy: how close a reported measurement is to the
true value of the quantity measured
• Precision: the degree of exactness or refinement of a
measurement

Sources of Error
Problems with accuracy are due to error
• Human Error: Mistakes made in reading an instrument or
recording the results
• Method Error: When measurements are taken using
different methods
• Parallax: An overestimate or underestimate due to the
improper viewing of a measuring device
• Instrumental Error: Improperly displayed measurements
due to poorly calibrated devices

Precision and Significant Figures
• Significant figures (Sig Figs) describe the precision of a
measuring device
• Significant Figures: those digits in a measurement that are
known with certainty plus the first digit that is uncertain

Review of Sig Fig Rules
Zero Rules:
• Zeros between other nonzero digits are significant
• 50.3 m has three sig figs
• Zeros in front of nonzero digits are not significant
• 0.553 m has three sig figs
• Zeros that follow a nonzero digit and are before or after a
decimal point are significant
• 50.00 has four sig figs

LETS PLAY: THE SIG FIG IS RIGHT
Determine how many sig figs
are in the following quantities:
1. 5.03 x 101 m
2. 3.0025 s
3. 8.92 x 10-1 kg
4. 0.8 x 10-4 ms
5. 5.700 x 101 g
6. 2.000000 kg
7. 2,100 kg
8. 0.75 cm
SIG FIG

Rules For Calculating Sig Figs
• Addition and Subtraction:
• Final answer should have the same number of sig figs to
the right of the decimal place as the number with the
smallest number of digits to the right of the decimal
• Multiplication and Division:
• The final answer should have the same number of sig figs
as the measurement having the smallest number of sig
figs

Rounding Rules
Keep the same if…
• If the digit after the last sig fig is less than 5
Ex: 30.24  30.2
• If the last sig fig is even, and the next digit is a 5 with no
other nonzero digits
Ex: 31.45  31.4 or 31.6500  31.6
Round up if…
• If the digit after the last sig fig is greater than five
Ex: 42.67  42.7
• If the digit after the last sig fig is a 5 followed by other
nonzero digits
Ex: 76.45001  76.5
• If the last sig fig is odd, and the next digit is a 5 with no
other nonzero digits
Ex: 54.75  54.8 or 79.3500  79.4

LETS PLAY: THE SIG FIG IS RIGHT...
AGAIN! (Bob Barker demands it!)
Determine what the final answer
would look like after performing
the indicated operation for the
following questions:
1. 97.3 km + 5.85 km
2. 123 s • 5.35 s
3. 57 kg + 3.021 kg • 74.3 kg
SIG FIG
AGAIN

Wrap Up
Answer the following questions in your group:
• Why are significant figures important?
• What steps could an experimenter take to ensure that their
experiment is as accurate as possible?

Objectives
• Interpret data in tables and graphs, and recognize
equations that summarize data
• Use dimensional analysis to check the validity of
expressions

The Language of Physics
• Mathematical equations are used to describe physical
phenomenon
• Learning to read a mathematical formula is like learning a
new language
• For example:
Equation Simple English
ΣF = ma
A net force is the result of some mass
undergoing an acceleration.

Common Symbols
Symbol Meaning
Δ difference, change in
Σ sum, total
g acceleration due to gravity
x displacement

Textbook Shorthand Note
• Any symbol written in standard font is to be considered a
unit
• Any symbol written in italic font is considered to be a
variable

Evaluating Physics Expressions
• Dimensional Analysis: the process of evaluating dimensions
in an equation to determine its validity
• Rules of Dimensional Analysis
• Quantities can only be added or subtracted if they have
the same dimensions
• The two sides of any given equation must have the same
dimensions
• Any dimension can be multiplied or divided by another
dimension

Dimensional Analysis Example 1
• Determine whether or not the following equation is
dimensionally consistent.
• Where v is measured in meters/second, x is measured in
meters, and t is measured in seconds.
𝑣 =
𝑥
𝑡

• Determine whether or not the following equation is
dimensionally consistent.
• Where x is measured in meters, t is measured in seconds,
and a is measured in meters per second squared.
• Solve the above equation for a, and determine whether or
not your new equation is dimensionally consistent.
Dimensional Analysis Example 2
Δ𝑥 =
1
2
𝑎 ⋅ 𝑡2

Homework
p. 18 #1, 5, 10
p. 19 #1, 2a, 6, 7, 9, 17

AP Physics 1 - Introduction

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AP Physics 1 - Introduction

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