Measurement Unit Part 2

10/24/15

In this lesson I understood pretty well because I read the section in the book the night before. We talked about accuracy and how that is the proximity of a measurement to the true value of a quantity. However precision is different by that it's the proximity of several measurements to each other. Think of it as a dart board with the red bulls eye in the middle of it. Accuracy would be throwing one dart and either hitting super close to the bulls eye or hitting the bulls eye. Precision is throwing 5 darts and hitting the bulls eye each single time. 

We also talked about scientific notation. If it had a negative exponent we would move the decimal to the left, but it the number had a positive exponent, you would move the decimal to the right. An example is 0.0803 which would turn into 8.03 x 10(-2 exponent). 3.45 x 10(6 exponent) would turn into 3,450,000. 

Significant figures refers to digits that were measured. It's important to know you can estimate 1 digit past the calibrated number!!! Ex. If it was 1.23 you can measure to 1.22 or 1.24 but not to 1.21 or 1.25.

So what zeros counts and don't count as a significant number? Well I'm glad you asked! 

Significant numbers and zeros practice!

13 = 2 sf and 0 zs

0.01040 = 4 sf and 2 zs

90 = 1 sf

90.0 = 3 sf

Adding/Subtracting SF:

The rule is you must use the number with the smallest number of decimal places as the limiting term

for rounding. Ex. 4.60 + 3 = 8.6 but 3 has zeros decimal places (limiting term) so it becomes 8

Multiplication and Dividing SF:

The rule is you must use the number with the smallest number of significant figures. 

Ex. 2.5 x 0.568 = 1.42 but 2.5 has 2 significant figures while 0.568 has 3. So 1.42 rounds to 1.4. 

Measurement conversions!!! 

King                         Kilo = 1,00

Hector                      Hecto = 100

Died                         Deka = 10

Drinking                  Deci = 0.1

Chocolate                Centi = 0.01

Milk                         Milli = 0.001

                                 Micro = 1x10⁶    

                                        Nano = 1x10⁹               

                                               

         Pico = 1x10¹²                         

Here are some helpful links! 

Metric Units

Significant Figure Rules

Video for Significant Figures