Measurement Session 3: Measurement Systems

Session 3, Part B:
Metric Units

In This Part: Length | Liquid Volume | Mass | Reasoning With Balance Scales

Knowing something about mass and how scales respond when objects are placed on them allows us to reason logically about weight or mass. For example, fake coins sometimes make their way into circulation, and balance scales can be used to determine which coins are fake. Let's explore this further. Note 13

Problem B15

a.	Imagine that you have three coins. One is heavier than normal, so you know it's a fake. But you cannot tell which one is the heavy one just by looking. What is the minimum number of weighings you would need to complete to find the fake coin?
b.	How would you find the fake coin among four coins? What is the minimum number of weighings needed?

c.	How would you find it among six coins? What is the minimum number of weighings needed?

Rather than weighing two coins at a time, think about how you could divide the coins into groups and then compare the groups to eliminate some coins. Close Tip

d.	How would you find it among eight coins? What is the minimum number of weighings needed? Note 14
e.	How would you find it among 12 coins? How many weighings would it take?

Video Segment
How is the metric system used in the United States today? Watch this video segment to find out how veterinary medicine uses it to provide the best and safest treatment for its patients.

Do you know of any other professional fields that rely on the metric system?

If you are using a VCR, you can find this segment on the session video approximately 21 minutes and 22 seconds after the Annenberg Media logo.

Next > Homework

Session 3: Index | Notes | Solutions | Video