Why red is used as a danger signal? plus 9 more videos..

Speed of sound - Why does sound travel faster in summer than in winter?
Ignition Temperature - Why does a match light when you strike it?
Latent heat of vaporization - Why do wet clothes feel cold?
Respiration - Why should we not overwater potted plants?
Transpiration - Why do cacti have spines?
Nerves - Why don't we feel pain when we cut our hair?
Wavelength - Why red is used as a danger signal?
Bad Conductors of Heat - Why are two thin blankets warmer than one thick blanket?
Breathing - Why do we get hiccups?
Latent Heat of Vaporization - Why does steam cause more severe burns than boiling water?