1. Measurements

2. What counts as a measurement?

3. Measurement Any time you find a numeric value to represent an object or event, it is a measurement

4. Examples Length of a football field Time it takes to run the 440 How many apples are in a bag

5. What can we really measure?

6. Only 3 things… Only 3 values need to be measured in for most “every day” things These are called the “Fundamental Indefinables”

7. Fundamental Indefinables Cannot be broken down into smaller parts Many other units of measure are made out of them

8. Length Length is measured in meters [m] Measures the separation, in space, between two points or objects

9. Time Time is measured in seconds [s] Measures the separation, in time, between two events

10. Mass Mass is measured in kilograms [kg] Measures the amount of matter that makes up an object

11. Complex Units Other units are made up of these fundamental parts

12. Examples Frequency –Hertz = 1/s Velocity –m/s Acceleration –m/s 2

13. Prefixes Using the metric system, we often run into prefixes before the actual unit These are really just mathematical constants Trust me, they are…

14. Common Ones Kilo- [k] = 10 3 –Ex. kilogram, kilometer Centi- [c] = 10 -2 –Ex. centimeter, centiliter Milli- [m] = 10 -3 –Ex. millimeter, milligram

15. Prefix Math When in doubt as to what to do with a prefix simply treat it as a math constant and just substitute in the value of the prefix

16. Example Convert 243 km into meters. k = 10 3 = 1000 243 x 1000 m = 243000 m

17. Precision The precision of your measurement is based on the measuring device It tells you how close multiple measurements will be to one another

18. Precision The precision of any tool is one-half of the least measurement the tool can make How to report it –Ex. 5.76 ± 0.5 mm

19. Accuracy The accuracy of a measurement is a comparison between the value you measured and the actual value of what you are measuring

20. Example You measure the gravitational acceleration of the Earth to be 10.1 m/s 2 We know that it is 9.8 m/s 2 The measured value is fairly close to the known, the value is rather accurate