1 / 16

Chapter 1

Chapter 1. The Nature of Science. Standards of Measurement. Accurate measurement is needed in a valid experiment. Standard —an exact quantity that people agree to use for comparison. In order for a measurement to make sense, it must include a number AND a unit .

chamomile-green
Download Presentation

Chapter 1

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 1 The Nature of Science

  2. Standards of Measurement • Accurate measurement is needed in a valid experiment. • Standard—an exact quantity that people agree to use for comparison. • In order for a measurement to make sense, it must include a number AND a unit. • Examples: 150ft, 35 cm, 64mi

  3. Measurement Systems • US: English system (pounds, feet, inches, Fahrenheit) • Most other nations: metric system • Science Worldwide:an improved version of the metric system called “International System of Units” or SI units. • SI comes from the French Le SystemeInternationaled’Unites • It is easier to convert units and share with others around the world.

  4. The SI System • SI Measurements and Base units • Base unit for length is the meter (m) • Converted unit: centimeter, kilometer • Base unit for massis the kilogram (kg) • Converted unit: gram, milligram • Base unit for time is the second (s) • Converted unit: microsecond • Base unit for electric current is the ampere (amp) • Base unit for temperature is the kelvin (K) • Base unit for volume is the liter (L)

  5. The SI System • The SI system is based on the number 10. • Prefixes are used with the names of the units to indicate multiples of 10. • Prefixmultiplying factor • kilo= 1000(thousand) • deci= 1/10 or 0.1(tenth) • centi= 1/100 or 0.01 (hundredth) • milli= 1/1000 or 0.001 (thousandth) • micro = 1/1,000,000or .000 001 (millionth) • nano = 1/1,000,000,000 or 0.000 000 001(billionth) Something Called SI

  6. Derived Units • Derived Unit: a unit that combines different SI units • Common Derived Units: • Area: cm2 or m2 • Volume: cm3 or m3 • Density: g/mL or g/cm3

  7. How can an aircraft carrier float?

  8. What is density? • It is a derived unit. • Density= mass divided by volume. • How do you determine mass? Use a balance. • Measure in grams or kilograms. • Mr. Edmonds Rock to an Oldie

  9. How do you determine volume? • We will express volume in cm3 and mL. • For a rectangular prism, V= L x W x H • For a liquid, measure volume using a graduated cylinder . • Find density first 90 seconds approximately no sig figs • Base units Meters Liters and Grams focus on liters

  10. Density=mass volume • Because 1 cm3 = 1 mL • Density=m (grams) = m (g) V (cm3) v (mL) Example: D=62.4 g/ (8.5 cm x 2.5 cm x 3.3cm)= D=62.4 g/ 70.1cm3 = .9 g/ cm3

  11. Accurate Measurement Readings • Read to the nearest mark, then estimate the number one decimal place further. 49.6 can be read with the lines on the ruler Estimate the last digit 4.4 can be read Estimate the last digit 6.1 can be read with the lines Estimate the last digit 49.66 cm 47.1 can be read with the lines on the ruler Estimate the last digit 47.10 cm

  12. Dimensional Analysis • Sometimes things need to be converted to different units. • You can use a conversion factor (a ratio) to change one unit to another. • Ex. 1 in = 2.54 cm • This process is called dimensional analysis

  13. Conversion Process 5 Steps of Dimensional Analysis • Start with the given (number & unit) • X (times) • Write the conversion factor as a fraction with the given unit on the bottom and new unit on top • Cross out units that cancel • Calculate & write the correct answer & units

  14. Example: How many centimeters is 6.74 in? • Start with the given (number & unit) • X (times) • Write the conversion factor as a fraction with the given unit on the bottom and new unit on top 1 in = 2.54 cm • Cross out units that cancel • Calculate & write the correct answer & units 2.54 cm 6.74 in X = 17.12 cm 1 in

  15. Metric Conversions: The Ladder Method.

  16. 1 2 3 MetersLitersGrams seconds How do you use the “ladder” method? 1 – Determine your starting point. 2 – Count the “jumps” to your ending point. 3 – Move the decimal the same number of jumps in the same direction. Starting Point Ending Point __. __. __. 2 3 1 Ladder Method KILO1000k HECTO100h DEKA10da DECI0.1d CENTI0.01c MILLI0.001m 4 km = ________m How many jumps does it take? 4. = 4000 m

More Related