Saturday, February 7, 2015
Touch something hot and your senses immediately tell you to pull your hand away. hotness is about the amount of heat energy an object has.
a spark from a firework may be very hot but it will not hurt very much becuse it does not contain much heat energy/however,even though a cup of tea may not be very hot,it can still burn the tongue because it contains a lot of heat energy
Friday, February 6, 2015
when light enters a material at an angle, it changes direction because its speed changes. if the material is very dense, the light slows down more and so the refraction is greater