unit 1, chapter 2 foundations of physics physics world1
TRANSCRIPT
Unit 1, Chapter 2
Foundations of Physics
Physics World 1
Unit 1: Measurement and Motion
• 2.1 Distance and Length• 2.2 Time• 2.3 Mass, Matter and the Atom
Chapter 2: Measurement and Units
Physics World 2
Chapter 2 Objectives1. 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
Physics World 4
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
Physics World 5
2.1 Distance and Length
measurement -
— a quantity and a unit
distance -
— is a length
— the amount of space between two points
Physics World 6
2.1 Two Systems of Units
Science problem solving requires both:
—Metric system
—English system
Physics World 7
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.
Physics World 8
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.
Physics World 9
2.1 Convert length
• A football field is 100 yards long.• What is this distance expressed in meters?
Physics World 10
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.
Physics World 11
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...
Physics World 12
2.2 Time
Key Question:How do we measure and describe time?
*Students read Section 2.2 AFTER Investigation 2.2
Physics World 13
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.
Physics World 14
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
Physics World 15
2.2 Time Units
Physics World 16
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.
Physics World 17
2.3 Mass, Matter and the Atom
Key Question:How is mass described?
*Students read Section 2.2 AFTER Investigation 2.3Physics World 18
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.
Physics World 19
2.3 Measuring Mass
• kilogram -– is the mass of 1 liter of
water or 1,000 cubic centimeters of water.
Physics World 20
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.Physics World 21
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.
Physics World 22
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.
Physics World 23
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.
Physics World 24
Physics World 25
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.
Physics World 26
Application: Nanotechnology
miniature cell pump micro T.V. mirrors smaller
than insect legs
Physics World 27
More Here
http://ap-physics.david-s.org
Physics World 28