Gross Earth & Solar System Structure

  • Find Earth’s mass from the acceleration of gravity by two methods: a ball drop using a commercial timer and photogate system, and timing several swings of a pendulum (works as well or better)
  • Discussing solar system formation, demonstrate conservation of angular momentum using a string connecting two balls threaded through a hole in the base of a cup. We set the upper ball swinging, so as the lower one slides down, the radius of the top one’s orbit decreases and it speeds up.
  • Racing a hoop and disk of the same mass down an inclined plane motivates the concept of moment of inertiaand leads to the idea of using a planet`s moment of inertia to learn about its core density.



The Galileo Project (A guided tour of Galileo’s life)

Il Museo della Storia delle Scienze, Firenze (A science museum in Florence with many artifacts from Galileo)

A Biography of Johanes Kepler

Data and images:

Moments of inertia for various shapes