1 / 15

# SI units and sig figs - PowerPoint PPT Presentation

SI units and sig figs. SI (système internationale). Precision: the reproducibility, under the same conditions, of a measurement . These points are precise with one another but not accurate. Accuracy: the closeness of a measurement to the true value of what is being measured.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about 'SI units and sig figs' - frye

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

### SI units and sig figs

Using sig figs: The Rules! of what is being measured.

• Digits from 1-9 are always significant.

• Zeros between two other significant digits are always significant

• One or more additional zeros to the right of both the decimal place and another significant digit are significant.

• Zeros used solely for spacing the decimal point (placeholders) are not significant.

Multiplying and Dividing of what is being measured.

• RULE: your answer may only show as many sig figs as the multiplied or divided measurement showing the least number of significant digits.

• Example: 22.37 cm x 3.10 cm = 69.3 only 3 sig figs allowed.

Adding and Subtracting: of what is being measured.

• RULE: your answer can only show as many decimal places as the measurement having the fewest number of decimal places.

• Example:

3.76 g + 14.83 g + 2.1 g = 20.7 g

Scientific Notation of what is being measured.

• Scientists have developed a shorter method to express very large numbers.

• Scientific Notation is based on powers of the base number 10.

• 123,000,000,000 in s.n. is of what is being measured.1.23 x 1011

• The first number 1.23 is called the coefficient. It must be between 1 - 9.99

• The second number is called the base . The base number 10 is always written in exponent form. In the number 1.23 x 1011 the number 11 is referred to as the exponent or power of ten.

To write a large number in scientific notation: of what is being measured.ex: 36 000

• First put the decimal after the first digit and drop the zeroes. Ex: 3.6

• Next, count the number of places from the decimal to the end of the number. Ex: 4

• Finally, put it together. Ex: 3.6 x 104

To write a small number in s.n. of what is being measured.ex: 0.00064

• First move the decimal after the first real number and drop the zeroes. Ex: 6.4

• Next, count the number of places moved from the original decimal spot to the new decimal spot. Ex: 4

• Numbers less than 1 will have a negative exponent. Ex: -4

• Finally, put it together. Ex: 6.4 x 10-4

Significant Digits of what is being measured.

• When using a measuring device, there is a last number estimation.

• The accuracy of the sig figs depends upon the measuring device.

• Ex: a ruler.

Read the ruler of what is being measured.

SI Prefixes of what is being measured.