Ellipse Board, 1L20.45

Topic and Concept:

• Gravity, 1L20. Orbits

Location:

• Floor Item: ME, North Wall

Abstract:

• The two pegs and string method for ellipse drawing on a whiteboard.

Important Setup Notes:

• N/A

Setup and Procedure:

1. Put two pegs in the holes on the board to be the desired focal points.
2. Hang the string loop over the two pegs.
3. Using the string pulled taught as a constraint, place the marker inside the loop, and draw the ellipse.

Cautions, Warnings, or Safety Concerns:

• N/A

Discussion:

The mathematical definition of an ellipse is the set of all points in the plane such that the sum of the distances to the point from the two foci is constant. This definition gives insight into why this drawing method should give an ellipse. Ellipses are a type of conic section that play an important role in orbital motion. They are a crucial ingredient in Kepler's laws.

Videos:

• Lecture Demonstration's Youtube Channel

References:

• Ellipse - Wikipedia

• Kepler's Laws - Wikipedia

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