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The Nature of Science

Section 2: Standards of Measurement. The Nature of Science. Units and Standards. A standard is an exact quantity that people agree to use to compare measurements. A standard is always exactly the same quantity when it is used anywhere in the world. Measurement Systems.

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The Nature of Science

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  1. Section 2: Standards of Measurement The Nature of Science

  2. Units and Standards • A standard is an exact quantity that people agree to use to compare measurements. • A standard is always exactly the same quantity when it is used anywhere in the world.

  3. Measurement Systems • A measurement is a way to describe the world using numbers. • For a measurement to make sense it must include a number and a unit. • The metric system of measurement is based on multiples of ten.

  4. The International System of Units (SI) • In 1960, the International System of Units was developed as an improvement to the metric system of measurement. • This system is abbreviated SI form the French Le SystemeInternationaled’Unites.

  5. SI Base Units • Each type SI measurement has a base unit • There are seven (7) base units used in the SI system of measurement.

  6. SI Prefixes • The SI system is easy to use because it is based on multiples of ten. • A prefix is added to the name of the base unit to indicate how many multiples of ten it should include.

  7. Quick review • What is science? • What is a standard? • What are the three (3) major categories of science? • Upon which numeric multiple is the metric system based? • How does science explain God? • Name the seven (7) base units in the SI system. • Identify three (3) ways of investigating the natural world. • How many nanoseconds are in 2 seconds of time?

  8. Measuring Distance • In science, the word length is used to describe the distance between two points. • Metric rulers and metersticks are commonly used to measure length. • A meterstick is a little bit longer than a yardstick.

  9. Choosing a Unit of Length • The unit you choose will depend on the object being measured. • By choosing the best unit, you can avoid very large or very small numbers.

  10. Measuring Volume • Volume is the amount of space an object fills. • The volume of a rectangular solid, such as a brick, is found by multiplying its length, width, and height (V=l x w x h). • Volume is expressed as a “cubic” amount.

  11. Practice Measuring Regular Volume • What is the volume of a 2m x 3m x4m moving truck? • Write the formula: (V= l x w x h) • Substitute given values: (V=2m x 3m x 4m) • Solve the equation: 24m3

  12. Measuring the Volume of a Liquid • To measure the volume of a liquid, you first must know how much liquid the container can hold. • Liquid is commonly measured in liters and milliliters. • 1 milliliter = 1 cm3

  13. Do you remember? • What is an independent variable? • Why is the dependent variable measured instead of the independent variable? • What is the volume of a brick that has a length of 20 cm, a width of 6 cm, and a height of 5 cm? • What are the most common units for expressing the volume of liquids?

  14. Measuring Matter • Mass is the measure of how much matter is in an object. • You can determine mass by using a balance.

  15. About Triple Beam Balances • A triple-beam balance gets its name because it has three beams that allow you to move known masses along the beam. • Because a triple beam balance compares a known mass to an unknown mass it is unaffected by gravity. Unlike a spring scale which really measures weight, the triple beam balance gives a true measure of mass.

  16. Density: Another Mass Measure • Density is the amount of mass in one cubic unit of volume of an object. • Density = mass/volume • If two objects are the same size and one object has a greater mass, it also has a greater density.

  17. Practice Calculating Density • Suppose an object weight 15 g and has a volume of 5 cm3. What is the density of the object? • Write the formula: D=m/v • Substitute given values: D=15 g/5 cm3 • Solve the equation: 3 g/cm3

  18. Measuring Time • Scientists need to keep track of how long it takes something to happen. • The unit of time in the SI system is second.

  19. Measuring Temperature • Commonly think of temperature as how hot/cold something is . . . • Three scales for measuring temperature • Fahrenheit • Celsius • Kelvin

  20. Fahrenheit Scale • Based on the temperature of the human body at 98.6º • Water freezes at 32º • Water boils at 212º

  21. Celsius Scale • Scientists use the Celsius scale to measure temperature. • Water freezes at 0ºC • Water boils at 100ºC • The scale is divided evenly into 100 degrees between freezing and boiling.

  22. Kelvin Scale • SI for measuring temperature is kelvin (K). • 0ºK is called absolute zero. • 0ºK = -273ºC • Divisions on the Kelvin scale are the same as the Celsius scale.

  23. Think about it . . . Sharon used a push-machine to thrust a basketball and a volleyball across a football field. The volleyball went farther than the basketball 9 out of 10 times. • What is the IV? DV? Constant (controlled variables)? • What can Sharon conclude about the density of the basketball? Why? • What other measurements can Sharon take to support her conclusions?

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