Chapter 2: Approaches to Problem Solving
Assignment #2 – Unit 2B
Standardized Units: More Problem-Solving Power
Pgs. 101 – 112
1. Briefly describe the origin and use of common units in the U.S. Customary
system.
The roots of US Customary units reach back to ancient Middle Eastern
civilizations. Foot was once the length of the foot of whoever was measuring;
Inch comes from Latin “uncia” meaning “thumb-width”. Mile comes from Latin
“milia passum” meaning “one thousand paces”. Yard – measurement from tip of
nose to tip of thumb. Grain – based on the weight of a typical grain of wheat.
2. Briefly describe the origin and use of metric units.
Invented in France late in the 18th century and now used throughout the world.
Designed for 2 primary reasons (1) to replace many customary units with just a
few basic units (2) to simplify conversions through use of a decimal system.
*Powers of 10*
3. What are the basic metric units of length, mass, time, and volume? How are the
metric prefixes used?
length – meter
*prefixes indicates multiplying by a power of 10
mass - kilogram
time – second
volume - liter
4. Using examples, show how to convert among the Fahrenheit, Celsius, and Kelvin
temperature scales.
Celsius to Fahrenheit: Multiply by 1.8. Then add 32.
Fahrenheit to Celsius: Subtract 32. Then divide by 1.8
Celsius to Kelvin: Add 273.15
Kelvin to Celsius: Subtract 273.15
5. What is energy? List at least three common units of energy. Under what
circumstances do the different units tend to be used?
Energy us what makes matter move or heat up. 3 common units of energy:
Calorie (measures the energy our bodies can draw from food), joule, watt,
kilowatt-hour
6. What is the difference between energy and power? What are the standardized
units for power?
Power is the rate at which energy is used, which means it has units of energy
divided by time.
The most common unit of power is the width, defined as 1 joule per second.
7. What do we mean by density? What do we mean by concentration? Describe
common units of density and concentration, including blood alcohol content, with
examples.
Density describes compactness or crowding.
- material density (g/cm3)
- population density (people/mi2)
- info density (MB/in2)
Concentration describes the amount of one substance mixed with another.
- concentration of an air pollutant (ppm)
- Blood alcohol content (gms./mL)
Exercises in your textbook: pgs. 114 – 116
#’s 18 – 28 ; 29 – 44 ; 45 – 52 ; 53 – 58 ; 59 – 68 ; 69 – 70 ; 71 – 72 ; 75 ; 76 ; 77 – 82
Additional examples: p. 115 83, 85, 93, 94