PRE-HEALTH_Center of Rotation for a Tooth
Instructions
This simulation shows an animation of the translation and rotation a tooth can undergo when changing position. The two images of teeth in the simulation show the initial (AB) and final position (A’B’) of a tooth. Clicking "animation" will show how the tooth moves from the unprimed to primed positions.
The objective is to determine the center of rotation by dragging it to the appropriate position relative to the two teeth diagrams (tolerance of 0.25 cm or a little larger than a square). To determine the center of rotation, use the black and red dotted lines are used to construct a point of intersection for AA' and BB'.
To get hints on how to do the construction to find the center of rotation, click “cycle hints.” This will eventually display the center of rotation.
The two black line segments are bisected by two red line segments where the angle between the lines is shown in green on the black line. The midpoint of the black line is shown with a red dot.
Take the black line segments and connect point A to A’ and point B to B’. Then take the corresponding red line and drag it over so the green angle is aligned with the red dot on the black line segment and is angled so it shows approximately 90°. Adjust the red lines so they intersect. The point where the red lines intersect while going through the midpoint of the black line at a right angle is the center of rotation.
Click the “submit” button to check the answer.
Click the “reset” button to clear the solutions and construction hints.
Created by Lewis Hicks and Priya Jamkhedkar for the Portland State University Physics Department, 2021.