1-1 What is Physics?  "Physics" is from the Greek root physik (science of nature) and Latin physica (natural science).  It’s the scientific study of matter, energy, force, and motion, and the way they relate to each other.  Studies how things work in the material universe. Chapter 1 The Science of Physics

watch?v=AEIn3T6nDAo&f eature=youtu.be Video – The Big bang tv show – “what is Physics?”

Physics explains things that are very, very large. Physics explains things that are very, very small.

1-2 Measurements in Experiments Scientific Notation  Extremely large or small numbers are expressed in powers of ten x x Rules:  When adding or subtracting numbers written in scientific notation exponents must be the same. Move the decimal point to the left you add one to the exponent, when moving decimal point to the right you subtract one from exponent.  When dividing 2 numbers written in scientific notation subtract exponents.  When multiplying 2 numbers add exponents. Example: 4.25 x x x 10 8 or 26.8 x 10 7 are equal – same value

Scientists use the International System of Units, or SI. Some Common SI base Units: Length – meter (m) Mass – kilogram (kg) Time – second (s) Thermodynamic Temperature – kelvin (K) Derived Units – units that came from a combination of other units Example: Newton and speed 1 kg / m/s 2 and m/s

The Metric System I’m ten times better than the Standard system of measurement!”

 Regardless of the unit, the entire metric system uses the same prefixes. Some common prefixes : giga = G x 10 9 or billions mega = M x 10 6 or millions kilo = k x 10 3 or thousands centi = c x or hundredths milli = m x or thousandths micro =  x or millionths nano = n x or billionths pico = p x or trillionths

 To convert measurements use Dimensional Analysis by multiplying by a conversion factor: (a factor equal to one.) Example: To convert 56 m to km --  56 m x 1 km = km 1000 m Example: Convert 65 mph to km/hr 65 mi/hr x 1.61 km/hr 1 mi /hr = 104 km/hr Conversion factor

Accuracy and Precision  Accuracy – describes how close a measurement is to the true value of the quantity measured.  Precision – measurements are close to each other. Results from the limitations of the measuring device.  Example: m is more precise than 45.0 m Low Accuracy High Precision High Accuracy Low Precision High Accuracy High Precision

Percent Error measures accuracy Scientific instruments always include an estimated digit. For example, using the centimeter ruler in Figure 1, the pencil might be recorded as having a length of 1.87cm. In this number, the “7” is the estimated digit. Another acceptable reading would be 1.88cm, but any other number of significant figures (or number of decimal places) would be incorrect. For example, 1.9cm would be an incorrect reading.

Significant Figures  Used to show the precision of a measured quantity  Include all digits that are actually measured plus one estimated digit.  Rules: 1) All non zero numbers are significant 738 = 3 sig figs = 5 sig figs 2) Zeros located between non-zero digits are significant 2014 = 4 sig figs This measurement should be read as 4.95 cm. This measurement has 3 significant figures.

3) Trailing zeros (at the end) are significant only if the number contains a decimal point; otherwise they are insignificant (they don’t count) 1.00 = 3 sig figs = 6 sig figs = only 3 sig figs 4) Zeros to the left of the first nonzero digit are insignificant (they don’t count); they are only placeholders = 3 sig figs = 2 sig figs

Rules for addition/subtraction problems  The number of decimal places in the result equals the number of decimal places in the least precise measurement  Example: =  Answer = 3 sig figs 25.3 (rounded up) Rules for multiplication/division problems  The number of sig figs in the result equals the number in the least precise measurement used in the calculation  Example: (27.2 x 15.63) ÷ =  Answer = 3 sig figs 230. (rounded down)

Copyright © MsRazz ChemClassMsRazz ChemClass Summary (Leading) Never sig. (Captive) Always sig. (Trailing) Sometimes sig. (decimal=sig.)

Copyright © MsRazz ChemClassMsRazz ChemClass Practice makes perfect! How many sig figs are in the following? , , x

1-3 The Language of Physics  Graphs and Charts  Symbols  In Physics there are 3 types of mathematical relationships that are most common. 1) linear relationship (or direct relationship) expressed by the equation y = mx + b where m is the slope and b is the y-intercept

2) Another relationship is the quadratic relationship. The equation is y = kx 2, where k is a constant.

3) The third equation is an inverse relationship, expressed by xy = k, where k is a constant.

Trigonometry will become important when we study vectors and parabolic motion Way to remember trig functions: “SOH CAH TOA”