Chapter 2 September 14 – October 20

Meme Moment

Scientist of the Day Extra Credit Only!

Scientist of the Day

Margaret Hamilton Started off as a teacher (math & French) Went back to grad school to learn about programming before it was even a thing Computer programmer for Apollo 11 mission Software design still used today Made sure moon landing happened Entrepreneur

Scientist of the Day

Colin Raston TODAY won an Ig Nobel Prize for unboiling an egg Ig Nobel Prizes are for silly research – it’s usually still useful Vortex fluidic device Invented a machine that fixes proteins

Scientist of the Day

Jonas Salk Invented polio vaccine people used to get polio in the US each year o 1/3 of them ended up partially paralyzed o Iron lung Funded by March of Dimes Refused to patent invention Polio now gone in all but 3 countries

Scientist of the Day

Youyou Tu Won Nobel Prize with 2 others last week o William C. Campbell o Satoshi Omura Isolated artemisinin (malaria drug) from traditional Chinese medicine o 2000 combos tried o Other 2 won for ivermectin (river blindness) Family killed in Cultural Revolution

Scientist of the Day

Dennis Ritchie Invented C programming language and Unix OS o With Ken Thompson Made them free so people could actually use them Like Margaret Hamilton, had to join a company to do PhD computer work o Never officially got his PhD Died the same week as Steve Jobs to little fanfare

Measurements September 15, 2015 (2.1 in your books)

Metric System Replaced weird measurements like “hands” or “cubits” that vary from place to place, as well as miles o A cubit is the length of your fingertip to your elbow Based around water, which is the same everywhere 1 g of water = 1 cm 3 = 1 mL (at 4ºC) Once you have a unit, you can add a prefix to save space. o The sun is 150,000,000,000 m away has a lot of 0s to keep track of o The sun is 150 billion m away has words in it, so you can’t do math o The sun is 150 Gm away(gigameters)

Imperial vs Metric MeasurementImperialMetric length inches, feet, yards, miles, leagues meter volume ounces, pints, quarts, gallons liter mass grains, pounds, stones, slugs gram

Who doesn’t use the metric system?

Prefixes SymbolPrefixMath10 n Example kkilox 1000x 10 3 kilo gram hhectox 100x 10 2 hecto meter dadekax 10x 10 1 deka liter x 1x 10 0 liter ddecix 0.1x deci meter ccentix 0.01x centi meter mmillix 0.001x milli gram Different ways of writing the same thing 6 th and 7 th grade

Prefixes SymbolPrefixMath10 n Example kkilox 1000x 10 3 kilo gram hhectox 100x 10 2 hecto meter dadekax 10x 10 1 deka meter x 1x 10 0 liter ddecix 0.1x deci meter ccentix 0.01x centi meter mmillix 0.001x milli gram µmicrox x micro liter nnanox x nano gram Different ways of writing the same thing 8 th grade

SI Units Fancier version of the metric system “International system of units” o The acronym doesn’t match because it’s international. o Acronym comes from the French version o S ystème I nternational d' Unit és 7 base quantities – if you know these, you can describe any quantitative measurement. Everything we know for certain is based on those 7 types of numbers We’ll use other units/descriptions/symbols like “energy” or “density” or “power,” but we can always trace them back to SI units o Energy = Joules = J = N·m = kg·m 2 /s 2

SI Units K = Kelvin = temperature s = second = time m = meter = length kg = mass = how heavy (ish) cd = candela = how bright mol = mole = amount of stuff A = ampere = electric current

Length Length: distance from one point to another SI unit = meter = m Estimating: 1 m ≈ 1 yard = 3 feet 1 cm ≈ the width of your finger 1 km ≈ 0.6 miles

Time Time: the period between 2 events SI unit = second = s Sometimes scientists get lazy and say “hours” or “days” instead of “____ kiloseconds” Milliseconds, etc are really popular in sports though!

Mass Mass: the amount of matter in an object Not the same as weight ! SI unit = kilogram = kg Weight: the pull of gravity on an object. Mass and weight only match on earth. In space, objects have 0 weight. A 5 kg object on earth still has 5 kg mass in space – just have to measure it differently!

Temperature Temperature: energy of molecules moving Molecules are always moving! Lots of moving = high temperature, hot Almost still = low temperature, cold SI unit = Kelvin = K Metric system also uses Celsius = ºC K = ºC

Temperature Scales

Breaking Down SI Units Common measurements like “volume” and “density” don’t have their own SI unit, but we can still trace their metric system name to an SI unit Volume = liter = L o How much 3D space something takes up o Everything is based on water, so 1 mL = 1 cm 3 o Going back to SI units, 1 L = m 3 = 1 dm 3 Density is commonly g/mL or g/cm 3 o Depends if you’re talking about liquid or solid o 1 g/mL = 1 g/cm 3, so they’re really the same thing o Example of “mixing and matching” SI units to make a new measurement

Volume Volume: Measures 3D space. Metric unit is liters (L). SI unit is cubic meters (m 3 ). Often use milliliters also (mL) Estimating: 1 coke can ≈ 350 mL 1 cup (for baking) ≈ 250 mL 1 gallon of milk ≈ 4 L

Measuring Volume Taller/longer is better than stumpy o Easier to see the measurements Measure at eye level Real number is at the bottom of the meniscus (the dip) o Water has a big meniscus because of adhesion – it likes to stick to other things! o Glass and mercury have an upside-down meniscus

Density Density: how much mass is in a given volume. SI unit = kg/m 3 Combines mass and volume. Common metric measurements are g/mL and g/cm 3 Things float if they are less dense than the liquid Things sink if they are more dense When things are the same substance, they always have the same density. o Water is always 1 g/mL (at 4ºC)

Density Formula

*just like we love comic sans. Not.

Eureka! Archimedes was asked to figure out if a crown was made of real gold and if it was all the gold the king had given to the jeweler. o It weighed the right amount, but what if another metal had been added to make up the difference? o He couldn’t do the normal tests because that would break the crown He yelled “Eureka!” when he figured out he could use density to test it o He stepped into a bath and it overflowed – displaced volume o We still use his method

Unit Conversions 1.Find the conversion factor. 1 km = 1000 m 2.Write it as a fraction (2 ways to do this). 3.You want the same unit on the top and the bottom.

Reminders 8 th grade Scientist of the Day presentations begin Monday Only presentation part Need 2 pictures Half a slide of bullet point facts Tell people if they’re right or wrong about subjective, qualitative, etc Turn it into a 2-minute story 8 th grade

Egg Engineering September 18, 2015

Egg Engineering 1.Find the mass of your egg. 2.Find the volume of your egg. 3.Calculate the density of your egg. 4.On Monday, we’re throwing the eggs out the window! Engineer a capsule so it doesn’t break. Goals: Protects the egg Works more than once ( repeated trial /rigor) You can get the egg out again

Estimates and Averages October 5, 2015 (2.2 in your books)

Accuracy vs Precision Accurate: close to the real answer Precise: close together Scientists want to be accurate AND precise !

Estimates When we’re working with really big numbers, we often estimate instead of counting to save time Scientists do this too! Especially with measurements. o When we use a beaker, graduated cylinder, etc, we estimate between the smallest marks to get a more accurate number. 50 mL 100 mL 150 mL 200 mL 125 mL estimate – even though there’s no mark here!

Averages When we have lots of estimates (or measurements ), we often want to find the average. The average is usually closest to the accurate (real) number. 3 Types of Averages Mean Median Mode

Mean Most common type of average Mean: the numerical average of a set of data Math: add up all the numbers, then divide by how many Computer shortcut: =average(B1:B4)

Median Often used in geography, etc. “Median income,” “median home price” Median: the middle number in an ordered set of data Math: Put the numbers in order, then find the one in the middle. If you have an even number, find the two middle numbers and divide by 2. Computer shortcut: =median(B1:B10)

Median Math: Put the numbers in order, then find the one in the middle. If you have an even number, find the two middle numbers and divide by 2.

Mode In French, “mode” means fashion! If it’s fashionable, lots of people have it Mode: the number that appears most often in a set. You can have more than 1 answer for mode. Math: have to look with your eyes Computer shortcut: =mode(B1:B10)

Estimates, Averages, and Sig Figs October 6, 2015 (2.2 in your books)

Percent Error

Range Range: the spread of data Math: biggest # - smallest # In high school/college you might have a different definition, but use this one for now.

Anomalous Data Sometimes you make a data set and one number looks really weird This is anomalous data Anomalous data is useful – it can tell you if your equipment isn’t working right, or maybe you forgot to control for a variable If your averages and percent error are strange, look for anomalous data

Significant Figures Significant figures = sig figs How scientists tell each other how precise a number is. Sig figs are made up of all the measured values (increments) + one that we estimate o Like how we measured volume in a beaker, then estimated in between the smallest marks From now on, all answers must be in sig figs ! Sig the Fig

Zeroes in Sig Figs A number that isn’t zero always counts Zeroes in the middle always count Zeroes at the start don’t count Zeroes at the end don’t count unless there’s a decimal NumberSignificant Parts# Sig Figs

More Sig Figs! NumberSignificant Parts# Sig Figs

Adding/Subtracting Sig Figs Use the smallest number of decimal places (or tens, hundreds, thousands, etc) Round to that number!

Multiplying/Dividing Sig Figs Use the smallest number of sig figs Round to that number!

More Stuff If you are using a conversion factor like “1000 g/ 1 kg” you have unlimited sig figs If you are using a counting number like “2 people,” you have unlimited sig figs

Homework Worksheet! It’s double-sided and due Friday. All answers must be in sig figs. Worksheet covers 2.1 and 2.2.

Graphs October 12, 2015 (2.3 in your books)

More Stuff about Sig Figs If you are using a conversion factor like “1000 g/ 1 kg” you have unlimited sig figs If you are using a counting number like “2 people,” you have unlimited sig figs

Anomalous Data Sometimes you make a data set and one number looks really weird This is anomalous data Anomalous data is useful – it can tell you if your equipment isn’t working right, or maybe you forgot to control for a variable If your averages and percent error are strange, look for anomalous data Graphs can help you spot anomalous data!

Graphs Graph: a picture of data that displays and compares information Axis/Axes: the straight lines in a graph that you plot data on *Outlier: a piece of data that doesn’t “fit” – often anomalous data Not these axes

Types of Graphs Bar graph o Vertical or horizontal o Can have more than one series at a time (use a legend/key if you have more than 1) o Good for counting and comparisons Line graph o Good for tracking changes Circle graph /pie chart o Good for comparing parts of a whole o Each section has to add up to 100%

Features of a Good Bar/Line Graph Title X-axis Y-axis X-axis subtitle Y-axis subtitle Units Key/legend Scale

Features of a Good Circle Graph/Pie Chart Title Labels Key Different colors Adds up to 100% What’s missing from this graph?

What does this chart tell you?

Linear vs Nonlinear linear nonlinear Neither linear nor nonlinear All of these are line graphs (lines connect & compare) There’s something wrong with each of these graphs. What is it each time?

Models and Systems October 19, 2015 (2.4 in your books)

Models Scientists and regular people use model differently Normal person: pretty person showing off clothes OR the best example OR a representation of an object or process Science: a representation of an object or process

Models A good model is different from symbolism (like in LA) because the representation has to work similarly to the real thing Models are used to test ideas that can’t be observed directly o Either because of cost, ethics, time, real thing is too big, have to test multiple ideas at once... What are some examples of hypotheses that must be tested with a model?

Systems System: a group of parts that work together to do something Input: thing that go into a system (material or energy) Process: action that happens inside the system Output: thing that comes out of a system (material or energy) Feedback: output that changes the system in some way (because it’s being input again)

Model/System

System

Atomic Models The atomic model changed a lot over 100 years, but it got a little better each time The cloud model in your books is incomplete o Atoms have more complicated shapes than spheres around them o Cloud model still works to explain most concepts

What does this chart/model tell you?

Old Questions What is the most dangerous big cat? What is the most dangerous fish apart from sharks? What kinds of water snakes are venomous? Where is West Nile virus and what does it do? Picture of largest snake? How many scientific laws are there? What is fugacity? How do spitting cobras work?