Chapter 1: the Science of Physics

Chapter 1: The Science of Physics PHYSICS IS EVERYWHERE! 1-1 WHAT IS PHYSICS? The Nature of Science: scientific law versus theory: Scientific law-

Scientific theory-

The Way Science Works… Science involves critical thinking, or applying logic and reason to observations and conclusions.

Observation vs. Inference: Observation-

Inference-

Variables and Controls: A variable is anything that can ______in an experiment. Independent variable: The variable being ______or ______by the scientist. Dependent variable: The variable being ______or ______by the scientist. A ______tests only one variable at a time.

The Scientific Method: A series of logical steps to follow in order to solve problems.  ______ FORMULATE A ______ FORM A ______ DESIGN AND CONDUCT AN ______ MAKE ______ ______AND ______DATA  DRAW ______ FORMULATE ______and ______

1-2 MEASUREMENTS IN EXPERIMENTS Making Measurements: measurements are made in this class using SI units. ______: distance between 2 points ______: space occupied. ______: the amount of matter in an object. ______: the force with which gravity pulls on a quantity of matter.

Converting Measurements: Move the decimal to convert between metric measurements. Ex: Convert 3.75 km to mm.

Use dimensional analysis when converting between other units. Ex: How many inches are in 1500 meters? Scientific Notation: scientist use special notation to express VERY LARGE or very small numbers.

Ex: 300,000,000 m/sec =

Ex: 1,007,000,000 sec =

Ex: 0.000 000 000 004 76 m =

Accuracy vs. Precision: Accuracy-

Precision-

(ex: a scale may be precise to the nearest 100th of a gram, or +/- 0.01g )

precision vs. accuracy

increasing precision

increasing accuracy Making Scientific Measurements  Measurements in science always have some amount of uncertainty in them.  The amount of uncertainty depends on the ______.  To record a better idea of the actual length of an object, you will have to ______the scale division marks.  This is done by estimating to the nearest one-tenth of the space between scale divisions.

Length: ______Length: ______Length: ______Because the last digit is an ______it might be ______from one person to the next. Example: A sample of liquid was recorded to have a volume of 23.01 mL. A. How far apart were the scale divisions on the graduated cylinder?

B. Which of the digits in the measurement is uncertain?

Significant Figures  All of the digits up to an including the estimated digit are called significant figures (or significant digits)  To determine if a digit is significant or not, you have to look at it’s placement with the decimal. o The building is 150 ft tall, the zero isn’t significant. o The block is 1.50 inches tall, the zero is significant. o The difference depends on the preciseness of the instrument used. Atlantic - Pacific Rule: (to determine number of sig. figs.) Decimal Present: Count from the Pacific side Decimal Absent: Count from the Atlantic side Start counting at the first non-zero number and count until you reach the end of the number Ex: 3.00700 decimal ______sig. figs. Ex: 300,700 decimal ______sig. figs.

Significant Figures in Calculations: When multiplying and dividing, limit and round to the ______number of ______in any of the factors. Ex: 23.0 x 432 x 19 =

The answer is expressed as ______or ______since 19 has only ___ sig. figs.

When adding and subtracting, limit and round your answer to the ______number of ______in any of the numbers involved in the calculation. Ex: 123.25 + 46.0 +86.257 =

The answer is expressed as ______since 46.0 has only _____ decimal place.

1-3 THE LANGUAGE OF PHYSICS

______IS THE LANGUAGE OF ______!

Organizing Data: data is organized and presented in tables, charts, and graphs. Graph - visual representation of data 1) title 2) x and y axis labeled 3) units for both the x and y axis 4) scale is evenly and correctly spaced for data 5) legend when appropriate

LINE GRAPH: best for displaying data that ______. – Independent Variable: ______– Dependent variable: ______

BAR GRAPH: useful when you want to ______data for several individual items.

PIE CHART: ideal for displaying data that are ______.

Percentage Error: Calculate this value in labs where the accepted value is given.

% error =

Order-of-magnitude Estimations: use this method to check the validity of your answers. Say you are dividing 725 km by 88 km/hour and you get 8.2 hr… Check:

The answer should be closer to ______than to 1 or 100. 8.2 hr – yes the answer is ______.

Trigonometry: Basic trig functions compare the ratio of two sides of a triangle to an angle in a triangle. Draw the triangle:

Sine: Arcsine:

Cosine: Arccosine:

Tangent: Arctangent:

Pythagorean’s Theorem (only for right triangles)

The Duffas Method for Solving ANY Physics Problem: D –