Physics Why does sound not travel in a vacuum? Why is the gravitational force of the Earth not able to pull a magnet off the refrigerator? How does a concrete boat float? Why is your image upside down in a spoon?

Physics The study of matter and energy The underlying science –Why do I call it the underlying science?

Safety Quiz Please take the safety contract home and have your parents sign it. Go on-line and take the on-line safety quiz. –You must complete this quiz before the Unit 1 Test or you will receive a 0 on the quiz and will not be allowed to participate any Unit 2 or above labs.

Syllabus and Course Needs You must get….. –Access to group fusion! –Composition Notebook –Binder (for notes and returned work) –Calculator –Ruler, protractor, graph paper are helpful

SI or Metric System Base units include length, mass, time, temperature, volume, etc.  Length – meter  Mass – kilogram*******  Volume – liter  Temperature – Kelvin  Time – seconds Derived units are combinations of base units such as velocity (meters / seconds). These are the standard units

Metric System Prefixes Peta (P) = base unit x Tera (T) = base unit x Giga (G) = base unit x 10 9 Mega (M) = base unit x 10 6 Kilo (k) = base unit x 10 3 Hecta (h) = base unit x 10 2 Deka (da) = base unit x 10 1

Metric System Prefixes Deci (d) = base unit x Centi (c) = base unit x Milli (m) = base unit x Micro () = base unit x Nano (n) = base unit x Pico (p) = base unit x

Working in STANDARD Units A snail travels a distance of 1,020 cm in 4.2 hours. What is the snail’s average velocity in standard units (meters/sec)? Solve for velocity –What conversions do you have to make? –Now convert to km/h

Algebra Review In physics, you need math skills. –Conversions and Measurements –Scientific Notation –Significant Figures –Geometry –Basic Trigonometry –Algebra In the next 30 minutes, we will BRIEFLY review some of the above.

Section A cm x 10 = 60 mm km x 1000 = 7,500 m x mg days x 24 x 60 x 60 = 216,000 seconds m 3 x (100 x 100 x 100) = 2,000,000 cm m/s x 3600 / 1000 = 37.8 km/hr

Section B 7.X = 30 8.X = 3 cm 9.X = 6.6 cm 10.X = 34 mm 11.X = 47 cm 12.X = 22.9 13.X = 50 14.X = 45 15. X = 117

Section C & D (2) (7 is incorrect but don’t count off!) x 10 8 or 1.29E8 (3) ,000 (2) x or 3.04E-5 (7) ,000,000 (2) x 10 1 or 8.263E1 (4)

Section E x x x 10 -4

Section F 25. x = d/v 26. x = 2(C-AB) D 27. x = 12y/ x = GmM F

Section G Driving distance is typically in KILOMETERS (1 km = 0.6 miles) Surface area of a paper measured in cm² (1 cm² = 0.16 in²) Volume of a soda can measured in liters (1 L = 1.1 quarts) Mass of a student should be in kilograms (1 kg = 2.2 lbs) Time is measured the same in both SI and English systems.

Labs Labs in physics involve –Making observations –Quantifying observations with measurements using the metric system –Developing relationships based on those observations

Models, Theories, Hypotheses and Laws A Model –A representation of something else A Theory –An explanation why something occurs supported by evidence A Hypothesis –An educated prediction about an outcome Law –A description of a relationship

Homework Questions? Scientific Notation Significant Figures –Sig Fig’s follow with equipment PRECISION! –Never have more sig figs than your measurement device can show.

Precision and Accuracy Precision –The degree of exactness of a measurement –Related to the number of sig fig’s that a measurement is known to –Can also be related to how tightly grouped the data is Accuracy –Is how close to the true value a measurement is to its true value.

Error Parallax Error –A viewing angle error on analog dials or when reading meniscus Systematic Error –An error that is equally present in all readings –Often from failure to zero or calibrate equipment Random Error –An error that is not present in all readings –Can be removed by taking multiple trials or averaging

Uncertainty Uncertainty is the degree to which you can know a measurement –Uncertainty is related to the smallest unit of measurement on a measuring device –Metersticks ± 1 mm –Most other equipment is ± ½ the smallest marked unit Percent Uncertainty –% unc = (total uncertainty / measured value) x 100

Graphing Terms X-axis: the horizontal axis, typically the independent variable Y-axis: the vertical axis, typically the dependent variable Gradient or Slope: the rise divided by the run Y-intercept: the y value corresponding to an x value of 0. Linear relationships: straight line on the graph Non-linear relationships: curved line on the graph

Graphing Rules Always label each axis with the variable and unit Always number your axis uniformly –You do NOT need to start numbering your axis at zero –Never “break” an axis or make it discontinuous Your data should take up at least half of each axis Always complete a graph with a best fit line or curve –Never connect the dots! –Best fit lines should have as many points above the line as below

Precision and Accuracy Lab Use the lab sheet to guide you through the lab. All questions must be thoroughly answered. Please attach an additional sheet of paper for the follow-up questions.

Test Next Block Math Skills –Scientific Notation –Significant Figures Metric System –Prefixes –Base and Standard Units Scientific Method –Models –Theories –Hypotheses –Laws Lab Skills –Precision and Accuracy –Uncertainty –Error Graphing Rules Lab Safety Syllabus and Course Requirements