1. Chapter 1 Introduction, Units, and Dimensional Analysis
Learning Objectives
Physics and the Laws of Nature
Units of Length, Mass, and Time
Dimensional Analysis
Converting Units
Order-of-Magnitude Calculations
Scalars and Vectors
Problem Solving in Physics
PowerPoint presentations are compiled from Walker 3rd Edition Instructor CD-ROM
and Dr. Daniel Bullock’s own resources

2. Why do we study physics?
Physics is the study of the fundamental laws of nature.
Aristotle  16th century
Galileo  Law of Inertia
Newton  17th century
Principia
Three laws of motion
Modern Physics  19th century

3. Mathematical Nature of Physics
Newton and Leibniz  Calculus
Mathematics is the only language precise enough to accurately describe the laws of nature.  isomorphism
Skills needed for success in this course
Algebra
Trigonometry
Vector Algebra
Graphical Analysis

4. Units used in Physics Fundamental units
Length (International System, SI  meter (m), British  foot (ft))
Mass (SI  gram (gr), British  slug (sl))
Time (SI & British  second (s))
Derived units – combinations of fundamental units
Speed (SI  m/s, British  ft/s)
Acceleration (SI  m/s2, British  ft/s2)
Force = mass × acceleration (SI  kg·m/s2 = Newton (N), British  pounds (lbs)

5. Units used in Physics Length: the meter
Was: one ten-millionth of the distance from the North Pole to the equator
Now: the distance traveled by light in a vacuum in 1/299,792,458 of a second

6. Units used in Physics Mass: the kilogram
One kilogram is the mass of a particular platinum-iridium cylinder kept at the International Bureau of Weights and Standards, Sèvres, France.

7. Units used in Physics Time: the second
One second is the time for radiation from a cesium-133 atom to complete 9,192,631,770 oscillation cycles.

8. Converting units in the SI system
SI system based on powers of ten
Each prefix represents a different power of ten
Kind
Hector
Decked
Mr.
Deci at the
Cinema on
Monday

9. Dimensional Analysis
Any valid physical formula must be dimensionally consistent – each term must have the same dimensions
From the table:
Distance = velocity × time
Velocity = acceleration × time
Energy = mass × (velocity)2

10. Converting Units Converting feet to meters:
1 m = ft (this is a conversion factor)
Or: 1 = 1 m / ft
316 ft × (1 m / ft) = 96.3 m
Note that the units cancel properly – this is the key to using
the conversion factor correctly!
Converting feet2 = meter2
316 ft2 × (1 m / ft)2 = m2

11. Scalars and Vectors
Scalar – a numerical value. May be positive or negative. Examples: temperature, speed, height
Vector – a quantity with both magnitude and direction. Examples: displacement (e.g., 10 feet north), force, magnetic field

12. Problem Solving in Physics
Read the problem carefully
Sketch the system
Visualize the physical process
Strategize
Identify appropriate equations
Solve the equations
Check your answer
Explore limits and special cases

13. Chapter 1 Summary
Physics is based on a small number of laws and principles
Units of length are meters; of mass, kilograms; and of time, seconds
All terms in an equation must have the same dimensions
Convert one unit to another by multiplying by their ratio
Scalars are numbers; vectors have both magnitude and direction
Problem solving: read, sketch, visualize, strategize, identify equations, solve, check, explore limits