Math, engineering, trades: steepness measurement: definition of grade
Tutoring math, you encounter grade. The tutor discusses its definition and why it might be surprising.
grade=100%*(rise/run).
By itself, rise/run is called slope.
Therefore,
grade=100%*slope
What follows is a distinction that, to me, is important and interesting:
rise/distance traveled
since, of course, you can’t drive along the horizontal course of a hill; rather, you can only drive on its surface.
At level, grade and (rise/distance traveled) are both zero. They remain virtually the same even at 20% grade, when (rise/distance traveled) is 19.6%. As the grade increases, however, they differ dramatically: at 100% grade, (rise/distance traveled) is 70.7%.
My interest in the difference between grade and (rise/distance traveled) is philosophical: why base a value on an indirect measurement (horizontal distance), when a direct measurement (distance traveled) is available?
In math, we use slope, of course; however, it’s usually in a context where actual measurements aren’t used. Rather, it’s just on paper.
Source:
Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.
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