The Metric System Why do I need to learn and be able to use the metric system?

WASHINGTON (AP) -- Failure to convert English measures to metric values caused the loss of the Mars Climate Orbiter, a spacecraft that smashed into the planet instead of reaching a safe orbit, a NASA investigation concluded Wednesday. The Mars Climate Orbiter, a key craft in the space agency's exploration of the red planet, vanished after a rocket firing September 23 that was supposed to put the spacecraft on orbit around Mars. CNN News Headline NASA: Human error caused loss of Mars orbiter November 10, 1999

SI System Scientists in different parts of the world need to be able to compare measurements/studies Scientists came together at a convention and created a standard system New system is based on a set of standard units used to measure things like mass, volume, temperature, etc. Named the system SI (System International)

Standard International Units (SI) Base Units QuantityUnitSymbol LengthMeterm Massgramg Molesmolemol TimeSeconds TemperatureKelvin (Celsius)K (°C) VolumeLiterL Light IntensityCandelaCd Electric CurrentAmpereA

Metric Conversions NameSymbol giga-G10 9 mega-M10 6 kilo-k10 3 deci-d10 -1 centi-c10 -2 milli-m10 -3 micro-μ10 -6 nano-n10 -9 pico-p10 -12

Dimensional Analysis (Factor Label Method) Follow these steps to set up a dimensional analysis problem 1. List all given information with the correct units. 2. Write down what you are trying to determine along with the correct unit. 3. List the conversion factors needed to solve the problem. 4. Write your given information as a fraction with the correct units. 5. Set up a chain of “fractions” (conversion factors) to convert from the given units to the desired units. To cancel out the original unit, place that same unit in the denominator where it will cancel out later. 6. Verify that all units cancel out except the units of the desired answer. 7. Do the math and record the final answer to the correct number of significant digits and in proper scientific notation. Include the correct units. 8. Circle your final answer.

Conversion Examples 230 grams = ? milligrams 34 ng = ? g

Conversion Examples 58Gg = ? g 278 Mm = ? pm

Conversion Examples 62 mmol = ? cmol 58 years = ? hours

Nanoscience 1 human hair is ~50,000 nanometers across; or 50 nanometers is one-thousandth the width of a human hair. 1 bacterial cell measures a few hundred nanometers across. The smallest things the naked eye can see are 10,000 nanometers. 1 nanometer = 10 hydrogen atoms in a line.

Why should I care about nanoparticles ? Using nanotechnology, Cornell scientists created a fabric that can detect biohazards like E. coli and other pathogens. Nanocrystals are used in photovoltaic cells as well as drug research Because it is being used now! Stain repellent clothing sunscreen Antibacterial paint in hospitals Untrathin glass treatment

Other Prefixes

How to Convert Learn the conversion factors. When moving from a large prefix to a smaller prefix your answer will always be a larger number. EX: 1 megameter = 10 7 decimeter When converting a small prefix to a larger prefix your answer will always be a smaller number. EX: 1 nanometer = centimeter

Dimensional Analysis Problem What is the size in cm of a 15 nm gold particle? 1.15 nm2. ?cm 3.1m = 10 9 nm and 1m = 100 cm 4.15 nm nm l 1m l100cm = 15 x cm 1 l 10 9 nm l 1m = 1.5 x cm