Transcript Document

CPO Science
Foundations of Physics
Unit 1, Chapter 2
Unit 1: Measurement and Motion
Chapter 2: Measurement and Units
 2.1 Distance and Length
 2.2 Time
 2.3 Mass, Matter and the Atom
Chapter 2 Objectives
1. Express lengths in metric and English units.
2. Convert distances between different units.
3. Calculate the surface area and volume of simple
shapes.
4. Describe time intervals in hours, minutes, and
seconds.
5. Convert time in mixed units to time in seconds.
6. Describe two effects you feel every day that are
created by mass.
7. Describe the mass of objects in grams and
kilograms.
8. Use scientific notation to represent large and
small numbers.
2.1 Distance and Length
Key Question:
How do we accurately communicate length and
distance?
*Students read Section 2.1 AFTER Investigation 2.1
Chapter 2 Vocabulary Terms









meter
centimeter
millimeter
kilometer
inch
foot mile
surface area
volume
weight










metric system
conversion factor
time
interval
precision
accuracy
kilogram
gram
mass
English system











atom
inertia
molecule
mixture
element
base
power of ten
exponent
scientific notation
distance
length
2.1 Distance and Length
 measurement — a quantity and a unit
 distance — is a length
— the amount of space
between two points
2.1 Two Systems of Units
 Science problem solving requires both:
— Metric system
— English system
2.1 Units of Length
 The common units of measurement in the English
system are inches, feet, yards, and miles.
 These four length units are related to the meter.
2.1 Convert Units
 conversion factor — is the number by which you
multiply or divide a quantity in
one unit to express the quantity
in a different unit.
2.1 Convert length
 A football field is 100 yards long.
 What is this distance expressed in meters?
2.1 Surface Area vs. Volume
 surface area — is the measurement of
the extent of an
object’s surface or
area without including
its thickness.
 volume — is a measure of the
space occupied by a
object.
2.1 Calculate surface area and volume
A basketball has a radius of 12.5 centimeters. Calculate
the surface area and volume of the ball.
1. You are asked to find surface area and volume.
2. A ball is shaped like a sphere and you are given the
radius.
3. Surface area: A = 4πr2; volume: V = (4/3)πr3
4. Solve...
2.2 Time
Key Question:
How do we measure and describe time?
*Students read Section 2.2 AFTER Investigation 2.2
2.2 Time
 Two ways to think about time:
— What time is it?
 3 P.M. Eastern Time on April 21, 2004,
— How much time has passed?
 3 hr: 44 min: 25 sec.
 A quantity of time is often called a time interval.
2.2 Converting Mixed Units
1.
2.
You are asked for time in seconds.
You are given a time interval in
mixed units.
1 hour = 3,600 sec
1 minute = 60
sec
3.
Do the conversion:
1 hour = 3,600 sec
26 minutes = 26 × 60 = 1,560 sec
4.
Add all the seconds:
t = 3,600 + 1,560 + 31.25 = 5,191.25 sec
2.2 Time Units
2.2 Accuracy and Precision
 accuracy
— is the quality of being exact and free from error.
— how close a measurement is to the true value.
 precision
— is the degree of mutual agreement among a series
of individual measurements, values, or results.
2.3 Mass, Matter and the Atom
Key Question:
How is mass described?
*Students read Section 2.2 AFTER Investigation 2.3
2.3 Mass, Matter and the Atom
 Mass
— is the amount of “stuff” an object contains.
 Two effects mass has on matter:
— weight
 is the force of the Earth’s gravity pulling down.
 Gravity acts on an object’s mass.
— inertia
 is the tendency of an object to resist changes in
motion.
 Inertia comes from mass.
2.3 Measuring Mass
 kilogram — is the mass of 1 liter of
water or 1,000 cubic
centimeters of water.
2.3 Scientific Notation
 Scientific notation works by expressing very
small or very large numbers as the product of
two numbers that are individually much easier to
deal with.
— The first number is called the base.
— The second number is a power of ten.
— The base is usually written with only one digit in
front of the decimal point.
 ex. 2,500 would be written 2.5 × 103
— The small numeral 3 in 103 is called the exponent.
2.3 Mass, Matter and the Atom
 atom — the smallest particle of an
element that can exist
alone or in combination
with other atoms.
 element
— composed of all of the
same kind of atom.
2.3 Mass, Matter and the Atom
 molecule — is a neutral group of atoms that are chemically bonded
together; it is the smallest particle of a compound that
can exist by itself and retain the properties of the
compound.
 mixture — is a substance that contains a combination of different
compounds and/or elements and be separated by
physical means.
2.3 Mass, Matter and the Atom
 The three most common forms of matter are
called solid, liquid, and gas.
 At temperatures greater than 11,000 °C the
atoms in a gas start to break apart and form
plasma.
2.3 Mass, Matter and the Atom
 Solids - Atoms in a solid stay together because the
energy per atom is too low to break the bonds between
atoms.
 Liquids- Liquids flow because atoms have enough
energy to move around by temporarily breaking and
reforming bonds with neighboring atoms.
 Gases- Gas atoms have enough energy to completely
break bonds with each other.
 Plasma- In plasma, matter becomes ionized as
electrons are broken loose from atoms.
Application: Nanotechnology
miniature cell pump
micro T.V. mirrors
smaller
than insect legs