1. Measurements All measurements include as many accurate numbers as possible and one estimated value. The numbers of accurate values a measurement has depends upon how the piece of equipment is graduated. Examples Examples

2. MASS MEASURES THE QUANTITY OF MATTER IN A SUBSTANCE BASIC UNIT- Kg kilogram INSTRUMENT - balance

3. WEIGHT Gravitational force between two bodies INSTRUMENT : scale BASIC UNIT: N newton

4. Volume/Capacity The amount of space occupied by something INSTRUMENT: Graduated cylinder UNIT: L Liters ( m 3 cubic meters) How many cm 3 in one m 3 ?

5. LENGTH Distance between two points INSTRUMENT: ruler UNITS: m meter

6. Temperature A measure of the average kinetic energy of a substance INSTRUMENT: thermometer UNITS: K kelvin (absolute scale) O C Celcius o F Fahrenheit Temperature and molecular motion Temperature scales

7. Celcius scale Devised by Anders Celcius in 1742 Based on the freezing point and boiling point of water. Diagram showing two fixed points:

8. Kelvin Scale Known as the absolute scale. Devised by William Kelvin A temperature scale on which the zero point would be absolute zero (theoretically the lowest possible temperature) and the size of the degree would be the same as celcius.

9. Note: a one degree change on the Kelvin scale is equal to a one degree change on the Celcius scale. Diagram:

10. K= C + 273 C = K - 273

11. PRECISION Precision refers to the degree of reproducibility of a measured quantity, that is, the closeness of agreement when the same quantity is measured several times

12. ACCURACY Accuracy : refers to how close a measured value is to the accepted or “real” value. High precision numbers are not always accurate. But it is more likely that measurements of high precision are more accurate.