2.1 distance and length 2.2 time 2.3 mass, matter and the atom
TRANSCRIPT
UNIT 2: MEASUREMENT AND MOTION
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 centimet
er millimete
r 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)πr34. 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. You are asked for time in seconds.2. 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 sec26 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