1 / 13

Journal 8/25/14

Journal 8/25/14. We know the number π to 10,000 decimal places or more. How do you think scientists and mathematicians measured it this well? Do you think there are other things we’ve measured this well too?. Objective Tonight’s Homework.

oriel
Télécharger la présentation

Journal 8/25/14

An Image/Link below is provided (as is) to download presentation 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. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Journal 8/25/14 We know the number π to 10,000 decimal places or more. How do you think scientists and mathematicians measured it this well? Do you think there are other things we’ve measured this well too? Objective Tonight’s Homework to learn the difference between accuracy and precision pp 26: 2.1, 2.4 pp 36: 5, 6, applying 5

  2. Notes: Accuracy and Precision We commonly use a dartboard as examples of accuracy and precision.

  3. Notes: Accuracy and Precision We commonly use a dartboard as examples of accuracy and precision. Not precise Precise Not precise Precise Not accurate Not accurate AccurateAccurate

  4. Notes: Accuracy and Precision Accuracy is a measure of how correct the number is. How close it is to the “right” value, or other accepted scientific measurements of the same thing. On a dartboard, if you’re aiming for the middle, you’re only accurate if you hit it.

  5. Notes: Accuracy and Precision Accuracy is a measure of how correct the number is. How close it is to the “right” value, or other accepted scientific measurements of the same thing. On a dartboard, if you’re aiming for the middle, you’re only accurate if you hit it. Precision is a measure of how well you know your measurement. Saying, “school is 7.32 miles from my house” is more precise than saying “school is about 7 miles from my house.” On a dartboard, precision is how consistent the throws are. How close they are to each other.

  6. Notes: Accuracy and Precision So how do we measure each of these? We can get accuracy through calibration. If I take a thermometer and put it in boiling water, I can test to see if it measures 100 °C. If it does, I know it is accurate. If not, I know I need to adjust it.

  7. Notes: Accuracy and Precision So how do we measure each of these? We can get accuracy through calibration. If I take a thermometer and put it in boiling water, I can test to see if it measures 100 °C. If it does, I know it is accurate. If not, I know I need to adjust it. We get precision through more and more detailed tools. A meterstick with 1,000 little marks can give us higher precision than one with just 10. Let’s talk about how to correctly show precision.

  8. Notes: Accuracy and Precision When taking measurements, we want to write the last certain number and the first uncertain one. A “certain” number is usually the smallest labeled marks on a tool. The “uncertain” number is usually a guess of how far the measurement is between the 2 nearest labeled marks.

  9. Notes: Accuracy and Precision Example: Write the correct precision for the measurement of the item below.

  10. Notes: Accuracy and Precision Example: Write the correct precision for the measurement of the item below. Our meterstick has markings down to millimeters, so our last certain point is 41.6 cm. It looks to be about halfway between 41.6 and 41.7, so our guess would be 41.65 cm. Most scientists would see this and say, “Ah. It could be as low as 41.6 cm, or as high as 41.7 cm.”

  11. Notes: Accuracy and Precision One last thing to note: If a measurement is right on a line, we say our “uncertain” measurement is “.0”. Saying “35.0 m” is very different from saying “35 m”. The first number could be as low as 34.9 m or as high as 35.1 m. The second could be as low as 34 m or as high as 36 m. That’s a very big difference in how well we’re saying we know the number!

  12. Practicing Measurement Your job for the rest of class is to grab a meterstick and measure the size of 10 objects in class. Measure down to the proper precision.  Measure 5 additional objects using a property different from length or size and with a different instrument than a meter stick. This will be due tomorrow. Remember, we record the last certain number and the first uncertain one. If you finish, you may start working on the homework.

  13. Exit Question #4 A man owns a thermometer with marks every 20 degrees. He looks at it one day and sees the temperature between 60 and 80. He estimates it’s about 69 degrees. What can we say about this thermometer? a) It’s not accurate b) It’s not precise c) It’s not accurate OR precise d) It’s accurate AND precise e) Not enough information

More Related