Hypathia incorrectly guesses how a sack will fall when it is dropped on a moving boat. She observes that the sack behaves as if the boat was stationary. Hypathia believes the same principle can be applied to the Earth: it is moving around the Sun without us realizing it.
Sheldon explains how he uses a toy train and a ball to prove Newton's first law of motion. As the train moves, he pushes a button to propel the ball in the air. The ball lands in the same spot on the train where it was propelled. The ball moves at a constant velocity in an inertial frame of reference.
The group of women encounter a chasm, and Juno tells everyone to freeze. She ignites a flame and tosses it across the chasm so they can inspect the obstacle they have encountered. She then throws a rock down the chasm in an attempt to measure its depth.