Find the length of a paperclip with each of the three “rulers”

• Ruler a

• Ruler b

• Ruler c

1. Were all of your measurements identical

2. Which measurement required the greatest degree of estimation

3. How do your measurements indicate the difference in degree of estimation>

Unit 1- Precision and Accuracy

• Accurate- Measurements that are close to the “correct” value – Bull’s eye

• Precise- Measurements that are close to each other.

Accuracy/Precision video

• Uncertainty in measurement video

Measurements… actual= 2.4cmStudent A Student B

Trial 1 2.5 cm 1.8cm

Trial 2 2.4 cm 1.7cm

Trial 3 2.3 cm 1.8cm

Average: 2.4cm 1.76cm

1. Were either of the students accurate? Which one? WHY?2. Were either of the students precise? Which one? WHY?3. Were either of the students both accurate and precise? Which one? WHY?

Uncertainty in measurement

• The last # which you estimate is the ____________• In this case, the uncertain # is _______• Measurements are only as precise as the _________

• When measuring this pin, its about 2.85.

Uncertainty in measurement

• The last # which you estimate is the UNCERTAIN NUMBER• In this case, the uncertain # is 5• Measurements are only as precise as the device

• When measuring this pin, its about 2.85.

Units Notes• Units: the scale that goes with numbers

• There are 3 systems: – English – in America (ex. Foot, pound)– Metric- EVERYWHERE (ex. Meter, gram)– SI – for science

• Based on metric

The Fundamental SI base unitsmeasurement

unit

abbreviation

instrument

picture

The Fundamental SI base unitsmeasurement Length

unit meter

abbreviation m

instrument ruler

Picture

The Fundamental SI base unitsmeasurement Length mass

unit meter kilogram

abbreviation m kg

instrument ruler Balance

picture

The Fundamental SI base unitsmeasurement Length mass volume

unit meter kilogram liter

abbreviation m kg l

instrument ruler Balance Graduated cylinder

picture

The Fundamental SI base unitsmeasurement Length mass volume temperature

unit meter kilogram

liter Kelvin

abbreviation m kg l K

instrument ruler Balance Graduated cylinder thermometer

picture

The Fundamental SI base unitsmeasurement Length mass volume temperature time

unit meter kilogram liter Kelvin second

abbreviation m kg l K s

instrument ruler Balance Graduated cylinder

thermometer stopwatch

picture

Mass• Mass = quantity of matter in an object.

• Weight= force exerted on an object by gravity.