Measurement and Units: Understanding Length, Time, and Mass

1. Unit 1, Chapter 2 CPO Science Foundations of Physics

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

3. Chapter 2 Objectives • Express lengths in metric and English units. • Convert distances between different units. • Calculate the surface area and volume of simple shapes. • Describe time intervals in hours, minutes, and seconds. • Convert time in mixed units to time in seconds. • Describe two effects you feel every day that are created by mass. • Describe the mass of objects in grams and kilograms. • Use scientific notation to represent large and small numbers.

4. Key Question: How do we accurately communicate length and distance? 2.1 Distance and Length *Students read Section 2.1 AFTER Investigation 2.1

5. meter centimeter millimeter kilometer inch foot mile surface area volume weight Chapter 2 Vocabulary Terms • 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

6. 2.1 Distance and Length • measurement - • a quantity and a unit • distance - • is a length • the amount of space between two points

7. 2.1 Two Systems of Units • Science problem solving requires both: • Metric system • English system

8. 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.

9. 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.

10. A football field is 100 yards long. What is this distance expressed in meters? 2.1 Convert length

11. 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.

12. 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. • You are asked to find surface area and volume. • A ball is shaped like a sphere and you are given the radius. • Surface area: A = 4πr2; volume: V = (4/3)πr3 • Solve...

13. Key Question: How do we measure and describe time? 2.2 Time *Students read Section 2.2 AFTER Investigation 2.2

14. 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 Time

15. 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 Do the conversion: 1 hour = 3,600 sec 26 minutes = 26 × 60 = 1,560 sec Add all the seconds: t = 3,600 + 1,560 + 31.25 = 5,191.25 sec 2.2 Converting Mixed Units

16. 2.2 Time Units

17. 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. 2.2 Accuracy and Precision

18. Key Question: How is mass described? 2.3 Mass, Matter and the Atom *Students read Section 2.2 AFTER Investigation 2.3

19. 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.

20. 2.3 Measuring Mass • kilogram - • is the mass of 1 liter of water or 1,000 cubic centimeters of water.

21. 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.

22. 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.

23. 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.

24. 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.

26. 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.

27. Application: Nanotechnology miniature cell pump micro T.V. mirrors smaller than insect legs