PASCO SE-9076 Constant Velocity Tubes - Manual (Page 11)

7
Constant Velocity Tubes 012–06697B
➤ In algebra, a graph of this type is described by the equation y = mx + b, where:
y is the quantity on the vertical axis,
x is the quantity on the horizontal axis,
m is the slope, and
b is the y-intercept (also called the vertical intercept).
By replacing each of these abstract symbols with the actual items dealt with in the
experiment, the mathematical equation can be transformed into a physics equation.
10. In the space below write the equation that results when you replace the symbols y and x
with the actual physical units, mass and volume in the equation for a straight line,
y = mx + b:
11. In the space below, substitute y-intercept value (360 grams) for b in the equation (notice
that the dimensional units grams are part of the value):
12. It is unlikely that your graph shows a y-intercept of exactly 360 g. What is the value of the
y-intercept, according to your graph?
13. Calculate the slope, m, as follows:
The slope, m, is found from the formula slope = rise / run. The first step in finding slope
is to mark two points directly on your best-fit line. Label these points so they won’t be
confused with data points. The farther apart you place them, the more accurate your result
will be. Choosing points that are on one of the grid lines will also improve your accuracy.
a) Select two points on the best-fit line, and read their coordinates from your graph:
First Point: y
1
-coordinate_____________ x
1
-coordinate______________
Second Point: y
2
-coordinate_____________ x
2
-coordinate______________
Did you remember to record the units of measurement, as well as the number?
b) Calculate the rise and run from these coordinates.
rise (y
2
- y
1
) = __________________ run (x
2
- x
1
)= __________________
Did you remember to record the units of measurement, as well as the number?