Driving forces of plate tectonics and the importance of inertia
Used this activity? Share your experiences and modifications
Simple in class calculations showing that inertia or momentum is completely unimportant in considering the driving forces of plate tectonics
This has been used both in introductory physical geology course for general science students and in more advanced course for geology/geophysics concentrators Designed for a geophysics course Designed for an introductory geology course
Skills and concepts that students must have mastered
How the activity is situated in the course
Part of a lecture on plate tectonics, prelude to the concept that forces acting on plates must balance
Content/concepts goals for this activity
Inertial terms or momentum completely unimportant when considering what controls plate motion
Higher order thinking skills goals for this activity
Making simple back-of-the-envelope calculations to test an idea
Other skills goals for this activity
Description of the activity/assignment
To demonstrate how unimportant inertia is in plate tectonic problems, as part of a lecture, we calculate momentum and moment of inertia of both a supertanker and a plate. A supertanker running into a dock will do more than a million times more damage than a plate. This activity addresses student misconceptions and has a small quantitative component.
Determining whether students have met the goals
Concept tested on an exam. Students remember this example for years, demonstrating its effectiveness at getting the concept across.
More information about assessment tools and techniques.
Teaching materials and tips