Sheldon tries to make friends by following the principles that Dale Carnegie has outlined in his book, "How to Win Friends and Influence People." His conversations are robotic, not authentic, and awkward as a result.
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.