Why do comets have tails? plus 9 more videos..

Comets - Why do comets have tails?
Lateral Inversion - Why is ambulance written in reverse?
Osmosis - How do fish drink water?
Gravity - Why are planets spherical?
Convex Lens - Can a magnifying glass burn paper?
Atmospheric Refraction - Why do stars twinkle?
Surface Tension - Why are drops spherical?
Water Purification - Why is alum added to water?
Resonance - How does sound break glass?
Properties of Liquids - Why is a diver able to cut through water in a swimming pool?