# Direct linear relationship physics and technology Here we establish a predictive linear relationship between insect catch VA, United States of America, Department of Physics, Virginia Tech, data repository for Virginia Tech, cypenv.info . and season-long cumulative catches A, which is a direct measure of the insect abundance. The numerical measure that assesses the strength of a linear relationship is give a definition of the correlation r,; discuss the calculation of r,; explain how to. This page contains a short article on direct and inverse relationships. being able to see qualitatively the relationships between variables is often crucial to an understanding of many technologies. Now look at a graph of how Y varies as we change X. As X increases in magnitude, Y increases in a linear fashion. This is.

For example, for any one-step change in x, is the change in y always going to be 3? Is it always going to be 5? If it's always going to be the same value, you're dealing with a linear function. If for each change in x--so over here x is always changing by 1, so since x is always changing by 1, the change in y's have to always be the same. If they're not, then we're dealing with a non-linear function. We can actually show that plotting out.

### Linear & Direct Relationships - Video & Lesson Transcript | cypenv.info

If the changes in x-- we're going by different values, if this went from 1 to 2 and then 2 to what you'd want to do, then, is divide the change in y by the change in x, and that should always be a constant. In fact, let me write that down. If something is linear, then the change in y over the change in x always constant. Now, in this example, the change in x's are always 1, right? So in this example, the change in x is always going to be 1.

So in order for this function to be linear, our change in y needs to be constant because we're just going to take that and divide it by 1. So let's see if our change in y is constant. When we go from 11 to 14, we go up by 3. When we go from 14 to 19, we go up by 5, so I already see that it is not constant.

## Linear & Direct Relationships

We didn't go up by 3 this time, we went up by 5. And here, we go up by 7. And here, we're going up by 9. So we're actually going up by increasing amounts, so we're definitely dealing with a non-linear function.

Direct and inverse variation - Rational expressions - Algebra II - Khan Academy

And we can see that if we graph it out. So let me draw-- I'll do a rough graph here. So let me make that my vertical axis, my y-axis. And we go all the way up to We call the line created from the data points of a graph a curve, even if it is straight.

For a linear relationship, we can represent the curve mathematically using the slope-intercept form of the equation of a line: We call this the slope-intercept form because here m is the slope, and b is the y-intercept.

### Direct and Inverse Relationships

The slope gives us a measure of the steepness of the curve, and the y-intercept tells us the point where the curve passes through the y-axis of the graph.

The last two variables, x and y, are the coordinates for any point on the curve. Let's look at an example of a linear relationship you might run into in a science course. Have you ever had to convert a temperature from Celsius to Fahrenheit?

## Recognizing linear functions

If you have, then you used the following formula to do so: When we graph a range of Fahrenheit temperatures vs. Celsius temperatures, we can see that it does indeed form a linear relationship. Celsius Direct Relationships In a direct relationship, as one variable increases, the other increases, or as one decreases, the other decreases. Often, you'll run across a special form of direct relationship called a directly proportional relationship where the variables are increasing or decreasing at the same rate and the curve passes through the origin, 0,0 point, of the graph. This is a special form of linear relationship that gives us a y-intercept of zero, changing our equation of a line to the following: In a directly proportional relationship, our slope is a constant, meaning it is a number that never changes.

For a directly proportional relationship, we call this the constant of proportionality. In an introductory physics course, you'll find that directly proportional relationships show up quite a lot. 