1. Measurement Systems

2. Suppose the label on a ball of string indicates that the length of the string is 150. Is the length 150 feet, 150 m, or 150 cm? For a measurement to make sense, it must include a number and a unit. 1.2 Standards of Measurement

3. International System of Units 1795: In France, a bunch of world- renowned scientists got together and decided on a standard system of units. (Le S ystème I nternational d’Unités) VolumeliterL Any combination of these units creates a derived unit.

4. Measurement Accurate measurements are a basic requirement in science. A standard is an exact quantity people agree to for comparison. Standards define each unit. Mass of a kilogram is compared to the international prototype kilogram made of platinum alloy

5. Mass The kilogram (kg) is the SI unit of mass. 1 kg = 2.205 pounds Measured using a balance/scale

6. The meter (m) is the SI unit of length. It is defined as the length of the path travelled by light in a vacuum during a time interval of 1/299,792,458 of a second. How many cm are in 1 m? Length is the distance between two points. Measuring Distance

7. Volume The SI unit for volume is the liter (L). V = l x w x h Liquid volumes are measured using a graduated cylinder Solid volumes are found by multiplication 1 mL = 1cm 3

8. Density Density is the mass of a material divided by its volume. substancedensity (g/cm 3 ) water1.0 aluminum2.7 lead11.3 mercury13.6 gold19.3 D=D= m V

9. The measurement unit for density: g/cm 3 (a combination of SI units = a derived unit) 1.2 Standards of Measurement

10. What’s Hot and What’s Not Temperature is the measure of how much heat something contains. 1.2 Standards of Measurement For most scientific work, temperature is measured on the Celsius (C) scale, where the freezing point of water is 0  C, and the boiling point of water is 100  C.

11. Time and Temperature The SI unit for time is the second (s). The SI unit for temperature is kelvin (K). degrees Celsius + 273 = kelvins Fahrenheit = 1.8C + 32 At what temperature does water freeze on the Kelvin scale? At what temp does it boil? 273 K, 373 K

12. Question 1 1.2 Section Check A __________ is an exact quantity that people agree to use to compare measurements. A.) variable B.) standard C.) unit D.) control SI standards are universally accepted and understood by scientists throughout the world. B!B!

13. Question 2 1.2 Section Check The amount of space occupied by an object is called _________? The answer is volume. To find the volume of a solid rectangle, measure the rectangle’s length by its width by its height. Answer