Talk and Listen

Talk directly into the ring while your friend listens at the ring of the other dish. Despite the great distance between the two dishes, you and your friend hear each other clearly. Why? As you talk into the ring, the sound waves travel from your mouth to the dish in front of you. From this dish, the sound waves are reflected toward the opposite dish where your friend is.

Echo Tube

Stand close to the exhibit. Clap your hand or say “HELLO” into the opening of the tube. Soon after, you will hear an echo of your clap or your voice. When you clap or speak into the tube, you create a disturbance of the air in the tube. The disturbance spreads out and bounces off the inside walls and closed end of the tube. When it travels back and reaches your ear, you hear an echo of your clap or voice.


Action and Reaction

Sit on the chair. Turn the pole of the umbrella slowly in one direction. In what direction does the platform turn? When you turn the umbrella in one direction, the platform moves in the opposite direction.

Every action has an equal and opposite reaction. This is Newton’s Third Law of Motion. It explains the relationship between the forces that two interacting bodies exert on each other. Forces always come in pairs. These pairs are equal in magnitude but opposite in direction.