Physical Science: Ch 1 Notes

1. Scientific method – a plan for gathering, organizing, and communicating information. • The goal of any scientific method is to solve a problem or to better understand an observed event. Physical Science: Ch 1 Notes Proper materials and variables are required to experiment with the Scientific Method Independent variable – this variable is purposefully changed and this causes change in another variable Dependent variable – this changes in response to the change in other variables Constant – a variable that does not change during the experiment Control – the standard to which experimental results can be compared

2. B. Standards of Measurement Standard - exact quantity that people agree to use for comparison Measurements must have a number and a unit!!!!! Physical Science: Ch 1 Notes SI (International System of Units)- an improved version of the metric system used and understood by scientists worldwide SI system is based on multiples of 10 and uses prefixes to indicate a specific multiple Length – the straight-line distance between two points (standard unit is meter) Volume - the amount of space taken up by an object (Liter is standard unit) Mass – the quantity of matter in an object or sample (kilogram is standard) Time is the interval between two events (seconds is standard)

3. C. Measuring Temperature Thermometer – an instrument that measures temperature, or how hot an object is Three different scales can be used to report temperature: Fahrenheit, Celsius, and Kelvin Physical Science: Ch 1 Notes Absolute Zero - the temperature where all particle motion stops While this cannot be achieved in the lab, scientists consider 0 K to be absolute zero

4. D. Scientific Theory vs. Law Scientific theory - a well-tested explanation for a set of observations or experimental results Theories are never proven but they become stronger if the facts continue to support them Physical Science: Ch 1 Notes Example: The kinetic theory of mattersays that all particles are in constant motion Scientific law - a statement that summarizes a pattern found in nature Laws do not attempt to explain patterns – the explanation is provided by a theory Example: The Law of Gravity is constantly proven but scientists cannot agree on a theory that explains how it works!

5. E. Organizing Data Scientists organize data by using data tables and graphs – this makes it easier to find trends and patterns Line graph – useful for showing changes that occur in related variables. Physical Science: Ch 1 Notes The independent variable is plotted on the x-axis (horizontal) The dependent variable is plotted on the y-axis (vertical) Slope – the ratio of a vertical change to the corresponding horizontal change Slope = rise/run Slope = y2-y1/x2-x1 Direction proportion – a relationship in which the ratio of the two variables is constant, so the graph is a straight line Bar graph – used to compare a set of measurements, amounts, or changes

6. F. Density - the ratio of an object’s mass to its volume D = mass/volume • The density of pure water is 1.00 g/cm3 or 1.00 g/mL • (1 mL = 1 cm3) Each metal on the Periodic Table of Elements has a specific density value – these values can be found in chemistry books and on the Internet Physical Science: Ch 1 Notes The displacement of water method allows us to find the volume (and then density) of irregular objects Step 1: Measure a volume of water in a graduated cylinder Step 2: Submerge the object in water Step 3: Measure the new water level in the graduated cylinder • Step 4: The difference in water volumes is the volume of the irregular object Substances that have a density of less than 1.00 g/mL will float on water