
On page 306, you learned that when one variable is a constant multiple of another variable, the pattern with the two variables is proportional. If you take a more advanced course in mathematics, you might see different words used, such as the two variables are "directly proportional" or "show direct variation." You might also see an equation, such as
where k is a nonzero number called the constant of proportionality. This equation can be read as "y is directly proportional to x." While you don't need to know how to write this equation for this text, one advantage of writing an equation is using it to make a table of values. For instance, in Example 5, you discovered the pattern "the distance the spring stretches is 3/2 times the weight in pounds." So, the constant of proportionality is k = 3/2 and you can write the equation
Using this equation, you can create the table below.

Drawing the human proportions can be tricky. For tips and tutorials on accurately drawing the human form, visit IDrawDigital.

 Elasticity is the tendency of a material to return to its original shape. This spring is more elastic since the same weight causes it to stretch less.
 You can see that the distance in inches the spring stretches is 3/4 times the weight in pounds. So if the weight is 7 pounds, the distance stretched is inches.

Comments (1)
These comments are not screened before publication. Constructive debate about the information on this page is welcome, but personal attacks are not. Please do not post comments that are commercial in nature or that violate copyright. Comments that we regard as obscene, defamatory, or intended to incite violence will be removed. If you find a comment offensive, you may flag it.
When posting a comment, you agree to our Terms of Use.Showing 1 commentsRon Larson (author)7 years ago I have always loved reading about the Scientific Revolution in Europe during the 1600s and 1700s. I like thinking about the discovery that much of nature works in predictable laws and patterns.0 0