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.
Beakman explains how gas is explosive and causes the combustion engine in the car to work. He uses a model engine with a side view and demonstrates what is happening with the gasoline when it explodes to move the engine parts. Beakman shows how the engine allows the wheels to turn by relating it to riding a bike. Up and down motion of the pedals is converted to turning the wheels through the chain. Same in the car with the pistons turning gears and thus the wheels.