Lesson 4: The Foucault Pendulum Plane of Oscillation Rotates

Maureen Dooley, B.S.Ed.

Copyright 2004. Permission is granted for classroom use and for non-commercial educational purposes.

Subject __________________________

Grade Level _______________________

Anticipatory Set (focus) -A warm-up question will be written on the board as the students walk into the room. Question: Imagine what happens if the while pendulum were to be turned in a circle. Would you be able to tell from the observation of the pendulums behavior what was moving?
The students will read the question and prepare to discuss their answers when class begins.

Purpose (objective) - The students will be able to observe that the plane of oscillation of the Foucault pendulum rotates, and they will record their measurements of the rotation on both a personal and class log.

Input - The teacher will ask for answers from the students to the question that they read from the board. The teacher will accept all answers and write them on the board. The teacher should not correct wrong answers, but accept all answers as possible correct answers. (Throughout the next several lessons, it will not be crucial that the students know the right answers yet, they will discover the right answers to these warm up and activity questions as the unit continues/closes.)

Modeling (show) -The teacher will demonstrate an arrow being pulled by two sides of the bowstring and flying in the plane defined by those two sides. The teacher will explain that the string and gravity pull the bob on the pendulum similarly, so that the pendulum should "go straight," moving in a plane defined by the string and "down." The direction of this plane of motion should not change because there is no sideways force. In particular the plane of motion "should" not rotate.

The teacher will then bring the students to the pendulum and tell them to walk around the pendulum in a circle and write down a description of the pendulum, giving a description of how their observations of the pendulum change as they move, and read and record the measurements from the clock-face (noting the time the measurements were taken).

Independent Practice - The students will walk around the pendulum in a circle and describe what they see and how their observations change as they move. Students will also read and record the measurements from the clock-face at the base of the pendulum; noting the times and the plane of oscillation; they should do this for 10-15 minutes; the time may be adjusted as needed.

Closure - (Tell or show me what you have learned) the teacher will ask the students what they described and how their observations changed/did not change. For example, forward/away motion changes to side-to-side and then to away/forward as they walk around the pendulum. The teacher will correct/concur and elaborate on their observations.

The teacher will begin writing down on the class log the measurements and times recorded by the class. The log will need to be updated each class period throughout the day and also at the beginning and end of the day by the teacher. The log will look something like this:

Date Time Direction
of swing
size of swing)
(time for one
round trip)
October 25, 2004  10:30 am east by northeast  20cm 6 seconds
October 25, 2004 12:30 pm  east 19 cm 6 seconds
October 25, 2004 1:30 pm east 18 cm 6 seconds
October 25, 2004 2:30 pm  east by southeast  20 cm 6 seconds