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Chapter 1

Chapter 1. Science Skills. Branches of Science. The Big Ideas of Physical Science. 1. Space and Time- The universe is very old and big . It is about 13.7 billion years old and we can observe 700 million billion billion meters in diameter.

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Chapter 1

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  1. Chapter 1 Science Skills

  2. Branches of Science

  3. The Big Ideas of Physical Science • 1. Space and Time- The universe is very old and big. It is about 13.7 billion years old and we can observe 700 million billion billion meters in diameter. • The four dimensions (Length, width, height and time). • 2. Matter and Change - Matter is anything with volume and mass. It can be a solid, liquid, or gas. The building blocks are called atoms. • Matter has mass and volume and can change forms.

  4. The Big Ideas of Physical Science • 3. Forces and Motion- Forces cause motion. If you push an object it will move.  The motion of cars on a city street is captured in this time-exposure photograph. Forces govern changes in the motion of each car.

  5. The Big Ideas of Physical Science • 4. Energy- Energy exists in many forms. Moving objects have a kind of energy called kinetic energy. An object that is not moving has stored energy, or potential energy. • Energy can be transferred from one form to another Panels on a solar car convert energy from the sun into the mechanical energy of its moving parts

  6. Scientific Method • Scientific Method is a step-by-steporganized plan for gathering, organizing, and communicatinginformation. STEPS 1. Make Observation 2. Ask Question 3. Develop Hypothesis 4.Experiment (include variables) 5. Analyze Data and Draw Conclusions - State if hypothesis is supported or not supported 6. Develop Theory

  7. Scientific Method Detailed • 1&2. Making observations - Information that you obtain from your senses that provides you with a question • 3. Develop a hypothesis - • Hypothesis – A proposed answer to a question. • It’s used to answer questions raised by one of your observations. In order for a hypothesis to be useful, it must be testable.

  8. Scientific Method • 4. Experiment or Testing a Hypothesis – Scientists perform experiments to test a hypothesis. In an experiment, any factor that can change is called a variable. • Variable- variable that causes change in another variable • Manipulated variable or independent variable- variable that causes a change in another variable. • Responding variable or dependent variable- variable that changes in response to the manipulated variable. • Controlled experiment- An experiment in which only one variable, the manipulated variable, is deliberately changed at a time. The responding variable is observed for changes, all other variables are kept constant, or controlled. • 5. Analyze Data and Draw Conclusions – See if your data from you experiment supports your hypothesis. If it does not, you must revise your hypothesis, or propose a new one. Then you must design a new experiment.

  9. Scientific Method • 6. Developing a Theory- Once a hypothesis has been supported in repeated experiments, scientists can begin to develop a theory. • Scientific theory- A well-tested explanation for a set of observations or experimental results. Theories are never proved. Instead, they become stronger if the facts continue to support them. Sometimes theories need to be revised. •  After repeated observations or experiments, scientists may arrive at scientific law. • Scientific law- A statement that summarizes a pattern found in nature. Example: gravity. A scientific law describes an observed pattern in nature without attempting to explain it. The explanation is provided by a scientific theory.

  10. Scientific Models • Model-Representation of an object or event. Example: maps • Scientific models make it easier to understand things that might be too difficult to observe directly. • It can be of a large object such as a car or solar system. • It can be of a small object such as a cell or atom.

  11. Section 1.3 • Scientific Notation – A way of expressing a value as the product of a number between 1 and 10 and a power of 10. • Example: 300,000,000 = 3.0 x 108 • The exponent 8 tells you the decimal point is really eight places to the right of 3. • Example: 0.00086 = 8.6 x 10-4 • The exponent -4 tells you the decimal point is really four places to the left of 8 Scientists estimate that there are more than 200 billion stars in the Milky Way galaxy.

  12. Math Practice • Perform the following calculations. Express your answers in scientific notation. • (7.6 × 10−4 m) × (1.5 × 107 m) • 0.00053 ÷ 29 • 2.Calculate how far light travels in 8.64 × 104 seconds. (Hint: The speed of light is about 3.0 × 108 m/s.)1.Perform the following calculations. Express your answers in scientific notation. • (7.6 × 10−4 m) × (1.5 × 107 m) • 0.00053 ÷ 29

  13. SI Units of Measure • All measurements need a number and a unit. • Example: 5 ft 3 in or 25ºF • Scientists usually do not use these units. They use a unit of measure called SI or International System of Units. • Base Units – more examples on following slide • Length- straight line distance between 2 points is the meter (m) • Mass- quantity of matter in an object or sample is the kilogram (kg)

  14. The International System of Units

  15. SI Units of Measure • Derived Units • These are units that are made from combinations of base units. • Volume- amount of space taken up by an object. l x w x h (m3) • Density- ratio of an object’s mass to its volume. D = m/v (kg/m3)

  16. SI Unit of Measure

  17. Metric Prefixes • 0.009 seconds = 9 milliseconds (ms) • 12 km = 12000 meters • Gigabyte = 1,000,000,000 bytes • Megapixel = 1,000,000 pixels • Some common prefixes: • Kilo- 1000 • Hecta- 100 • Deka- 10 • (base unit) 1 • Deci- 0.1 • Centi- 0.01 • Milli- 0.001 Nutrition labels often have some measurements listed in grams and milligrams

  18. Conversion Factors • Conversion Factors- Ratio of equivalent measurements that is used to convert a quantity expressed in one unit to another unit. • Examples: 1 km or 1000 m • 1000 m 1 km • 1000 m = 100 Dm = 10 hm = 1 km

  19. Primary conversion factor: 8848m ( 1km ) = 8.848 km 1000m • Secondary conversion factor: • 12 km (1000m) (1000mm) = 1.2 x 107 mm or 12,000,000 mm 1km 1m  • Tertiary conversion factor: • 5 km(1000m) ( 1hr ) = 1.39 m/sec 1 hr 1 km 3600sec

  20. Limits of Measurement • Precision- A gauge of how exact a measurement is • Significant figures- all the digits that are known in a measurement, plus the last digit is estimated. 5.25 minutes has 3 significant figures. 5 minutes has 1 significant figure. • The fewer the significant figures, the less precise the measurement is. • The precision of a calculated answer is limited by the least precise measurement used in the calculation. • Example: Density = 34.73g = 7.857466 g/cm3 4.42cm3 • You must round to 3 significant figures: 7.86 g/cm3

  21. Accuracy- Closeness of a measurement to the actual value of what is being measured. • Example: A clock running fast will be precise to the nearest second, but it won’t be accurate, or close to the correct time. A more precise time can be read from the digital clock than can be read from the analog clock. The digital clock is precise to the nearest second, while the analog clock is precise to the nearest minute.

  22. Measuring Temperature • Thermometer- An instrument that measures temperature, or how hot an object is. • Fahrenheit scale: water freezes at 32ºF and boils at 212 ºF  • Celsius scale: water freezes at 0ºC and boils at 100 ºC  • ºC = 5 (ºF- 32) ºF = 9 ºC + 32 9 5 • The SI unit for temperature is the kelvin (K) • 0K is the lowest possible temperature that can be reached. • In ºC, it is -273.15 ºC • K = ºC + 273 ºC = K – 273

  23. Section 1.4 • Organizing Data • Scientists can organize their data by using data tables and graphs • Data table- the simplest way to organize data. The table shows two variables - a manipulated variable and the responding variable. 

  24. Line graph • Line graphs are useful for showing changes that occur in related variables. It shows the manipulated variable on the x-axis and the responding variable on the y-axis. • Slope- (steepness) The ratio of a vertical change to the corresponding horizontal change. • Slope = Rise Run • Rise represents the change in the y-variable • Run represents the corresponding change in the x-variable.

  25. Direct proportion- Relationship in which the ratio of the two variables is constant. Inverse proportion- Relationship in which the product of the two variables is constant.

  26. Bar graphs and pie or circle graphs can also be used to display data.

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