The Scientific Method The Scientific Method l 7

The Scientific Method

The Scientific Method l 7 steps of the scientific method 1. 2. 3. 4. 5. 6. 7. Report you findings

Observation May be the most important step. Before you can really do anything, you must first notice that something needs to be done. Observation is really recognizing a discrepancy. Astronomers who relied on their powers of Observation: Galileo, Newton, Ptolemy

Statement of the problem l Always written as a “ l l ” question. What is the effect of increased temperature on cricket chirps? What is the effect of increased speed on fuel consumption? l Stating the observed discrepancy in the manner of a question allows one to develop an answer. l What questions lead to a cause and effect. “Why” questions can be answered with a simple “because”.

hypothesis Defined as an _________ l The hypothesis is what you think is the best answer to the question you posed when you stated the problem. l Best when written as a cause and effect. l When developing a hypothesis, always keep in mind the original observation, and the problem that you are trying to answer. l

Designing an experiment l Experiment- is which addresses a particular problem. l What are some things to think about when designing an Experiment?

Things to think about when designing an experiment l l l Materials that are readily available

Parts of an experiment l l l Control: Aspect of the experiment that is held constant so as to have a standard of comparison. _________: the factor that is adjusted by the experimenter. : The factor which changes as a result of the independent variable l The dependent variable depends on the independent variable

Experiment (continued) : part of the experiment that is used as a control. l Constant: l l : group with in the experiment which all things are the same as the control group except for one aspect, which is referred to as the _____.

Collect and analyze data After the experiment has been conducted, data must be collected analyzed. Things to think about: l

Draw Conclusions are judgments based on an experience and the interpretation of data. Conclusions can be different. We all have different experience Some conclusions are better than others. The difference between a good astronomer and an average astronomer may be the ability to draw relevant conclusions.

Report findings l l In the field of Astronomical research this entails writing papers Basically you are responsible for informing the community of your results You recognized a gap in our knowledge about the world around us. Once you know the information you need to tell the public so as to fill the gap. That means being able to properly communicate

The cyclical nature of science l If your hypothesis is not proven correct by your experiment you must reject it, and draw whatever conclusions that you can then develop a new hypothesis and experiment.

Theory When conclusions associated with a specific hypothesis are continuously supported by many different experiments then the hypothesis is considered a theory l When a theory is continually support and considered to be a rule of nature then it is said to be a law. l

The Nature of Science Types of reason l l : reasoning from a particular set of facts to a general rule. : suggesting something is true about a specific case from a known general rule. Types of research l l : controlled experiments that result in counts or measures. Numerical data : observational data often descriptions of observations of animal behavior.

Science and Society l l l Society must take responsibility for how a scientific discovery is used. But science is limited to addressing questions that can be answered using the scientific method, and the methods MUST be ethical. A scientist does NOT decide what is ethical and what is not, rather society dictates the ethical guidelines that a scientist must adhere to. Ethics- is a study of the standards of right and wrong. Technology- The application of scientific research to society’s needs and problems.

Metric System

International system of measurements In 1975 the United States passed the Metric Conversion Act. The intent was for the U. S. to use the metric system like the rest of the world. What happened instead was that metric units were placed on labels in addition to the standard units l We will use metric units in this class l

Prefixes l Prefix Symbol l l k d c m l l n x factor 1000 0. 1 0. 001 0. 000000001

Units of Measure l Length l Meter (m) l 1 meter = _____ centimeters (cm) l 10 mm=1 cm=0. 1 dm=0. 01 m=0. 00001 km l Examples 7 m = _____ cm = _______ mm l 7 m = _____ km l 92 m = _____ km l 550 cm = _______ m l 3. 6 m = ____ mm l

Units of Measure Notice there were no units for EXTREMELY large distances. l In astronomy there are SEVERAL units of measure for great distances: l Astronomical Unit (AU) – ________________________________________ l l 1 AU = 1. 5 x 1010 m or 150 million km l l Light year - (NOT A UNIT OF TIME!) The distance that _____ travels in a _____. l l Mercury = 0. 4 AU from the Sun Earth = 1 AU from the Sun Pluto = 40 AU from the Sun Light travels 9. 46 x 1015 m in on year Parsec – Distance at which an observer sees the maximum angle between the Sun and the Earth to be one arc second. (We may discuss this later, we most likely will not be using parsecs as a unit of measure. ) l 1 parsec = 3. 26 light years (3. 09 x 1013 km).

Units of Measure l Mass l The amount of ______ in an object l We will work mainly in _____ l 1000 grams (g) = 1 Kilogram (kg) l 1 gram = 1000 milligrams (mg) l Examples 4. 601 kg = 4601 g l 9 g = 9000 mg l

Units of Measure l l Volume: the amount of space an object occupies. SI (System International) for volume is the _____ (L) 1000 L = 1 kiloliters (k. L) We will mostly be using ________ (ml) l l 1000 m. L = 1 L The great thing about SI (System International) is that 1 m. L = ______ Volume can be easily converted to m. L or L from the measurement of length Meniscus – the curved surface of a liquid.

Units of Measure Density= __________ l Used to identify an object l D = M/V l Units is g/ml or g/cm 3 l How many grams is a substance if it has a density of 19. 3 and a volume of 3. 6 ml? Answer = 69 g l

Units of Measure l Time and Temperature l l l Time is measured in seconds Temperature is actually a measure of the kinetic energy of a substance (how quickly the molecules that make up a substance are moving) Temperature is measured in Kelvin or Celsius We will use _______ Water freezes at _____o. C and boils at ______o. C Body temp is about 37 o. C

Kelvin (K) l l Kelvin (K) is mostly used in Chemistry and Physics O K is called ____________ Absolute zero is when molecular motions stops. It is impossible to get anything colder than absolute zero. That means that there are no negative temperatures in Kelvin. To convert between Celsius (C) and Kelvin (K): C + 273 = K l K – 273 = C l l Water boils at 373 K and freezes at 273 K

Odds and Ends l Accuracy: how close your value is to the actual value- this gets better with practice. l Accuracy depends on U Precision: indicated by the number of significant digits and depends on the quality of the measuring instrument. l Significant digits are the numbers off the measuring device. l

The Basics l Planet – A large body in orbit around a star. Must be mostly have a path. l l l Examples: Our moon, Ganymede, Io, Europa. Solar System – The Sun, planets, their moons and other bodies that orbit the Sun. Our Sun is a star. – A massive, gaseous body held together by gravity and generally emitting light. l l Planets in our solar system (9): Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, (Pluto). – A body orbiting a planet. l l and Normal stars generate energy by nuclear reactions in their interiors. – The path in space followed by a celestial body. ALL celestial bodies rise in the East and set in the West. A result of the rotation of the Earth. – The drift of a planet westward against the background of stars. l l Normally planets shift eastward because of orbital motion. The planet does NOT actually reverse its motion. The change in direction is caused by the change in position from which we view the planet as the Earth overtakes and passes it.

Solstice versus equinox l l - the path traced by the sun as it crosses the celestial sphere. Solstice (winter and summer) – The beginning of winter and summer. The solstice occurs when the sun is at its greatest distance north (in June) or south (in December) of the celestial equator. l l l Summer solstice – Near June 21 Winter solstice – Near December 21 – The time of the year when the number of hours of daylight and night are approximately equal. The spring and fall (vernal and autumnal) equinoxes mark the beginning of spring and fall seasons. l l Spring (vernal) equinox – March 21 - start of spring Fall (autumnal) equinox – Near September 21 - start of autumn

Eclipses One will occur in Sept. - Visible in S. Am. l Occurs when the moon happens to lie exactly between the Earth and Sun, or when the Earth lies exactly between the Sun and Moon. l All three bodies will be in a straight line l There are two types of Eclipses l l Lunar Eclipse l Solar Eclipse

Eclipses Lunar Eclipse – Occurs when the Earth passes between the Sun and the Moon, casting its shadow on the moon. (Fig 1. 15) l Solar Eclipse – Occurs when the Moon passes between the Sun and the Earth, blocking our view of the Sun. (Fig 1. 14) l

Ellipse Do not confuse an ellipse with an eclipse. l An ELLIPSE is a geometric shape, similar to a circle, but elongated in one direction. l The path of the Earth’s orbit around the Sun is in the shape of an ellipse. l