Foucault Pendulum
Figure 1. Sixth-grade students interact with the Foucault pendulum demonstration.Copyright 2012 Jeffrey Laut, Polytechnic Institute of NYU
Students learn about the Foucault pendulum—an engineering tool used to demonstrate and measure the Earth's rotation. Student groups create small experimental versions, each comprised of a pendulum and a video camera mounted on a rotating platform actuated by a LEGO® MINDSTORMS® EV3 motor. When the platform is fixed, the pendulum motion forms a line, as observed in the recorded video. When the rotating, the pendulum's motion is observed as a set of spirals with a common center. Observing the patterns that the pendulum bob makes when the platform is rotating provides insight as to how a full-size Foucault pendulum operates. It helps students understand some of the physical phenomena induced by the Earth's rotation, as well as the tricky concept of how the perception of movement varies, depending on one's frame of reference.
Students get a taste of mechanical engineering and computer science, first by building a rotating chassis to carry a video camera and mounting a pendulum on a fixed support, then by running (provided) software programs from the LEGO EV3 brick to control the rotating chassis motion. Then they compare the fixed vs. in-motion camera video recordings of the pendulum movement in order to make an analytical inference, similar to what practicing engineers do. The rotation of the Earth plays a pervasive role in the natural phenomena of our world, and hence in science and engineering. The Earth's rotation causes the Coriolis effect, and the rate of rotation is taken into consideration by engineers who examine wind patterns and ocean currents, make weather prediction models, study long-range projectile motion, and plan flight paths and launch rockets (trajectories).
After this activity, students should be able to:
- Relate the effect of the Earth's rotation to the formation and movement of winds such as typhoons and cyclones.
- Explain why engineers must take into consideration the Earth's rotation when designing and launching missiles.
- Describe how a Foucault pendulum is used to exhibit and measure the Earth's rotation.