Graphing

Why is graphing important?

Pictures are easier than complicated math!

They are useful for analyzing relationships.

Axes

What is the x axis for?

Independent Variable

Dependant Variable

What is the y axis for?

Independent Variable

Definition: Variable that is the cause of change in the system.

Think of the letter x. It has 2 legs, it stands on its own!

Very often our independent variable will be time.

Dependent Variable

Definition: the variable that shows the effect of the changes in the experiment.

Think of the letter y. It only has one leg so it needs to depend on others to hold itself up.

Label Axes

10 1

20 2

30 3

40 4

Dist (m) Time (s)

time(s)

distance(m)

Title

time(s)

distance(m)

Always title it y vs. xLeft side of your graph to right side, just like you read

Distance vs. Time

Scaling

WARNING!!! Graph breaking is absolutely not allowed!

time(s)

distance(m)

Distance vs. Time

ScalingChoose an appropriate scale for each axis.Never skip different amounts of numbers within an axis!

Ex:Don’t

0 5 10 20 50

Do

0 5 10 15 20

Line of best fit

time(s)

distance(m)

Distance vs. Time

. .

. .

.

It is a straight line that does not need to pass through all of your plotted points.

Slope

To find the slope of a line choose two different points along your best fit line

Remember: (x,y)

Write the coordinate of both of the points you chose.

1st Coordinate(x1, y1)

2nd Coordinate(x2, y2)

Slope

Slope = Rise over Run

Slope = y2 - y1

x2 - x1

=∆y

∆x∆ = delta = “change in”

So for our graph from before, since the y axis had distance and the x axis had time, y/x is the same as distance divided by time or: m/s