Why will insulators affect how long a test tube of hot water stays hot?
I know that there are many different ways of insulating this test tube, shiny foil can be used because it's a poor emitter of radiation and it will reflect escaping heat by reflecting, because this method is used in flasks to keep hot drinks warm. Though it is a good conductor so will lose heat through to surfaces its touching but it shouldn't matter because it will be touching air and glass which both are really poor conductors. Bubble wrap, foaming and cotton wool can be used as an insulator because it will trap heat in air pockets and air is a poor conductor of heat, hence it will be a good insulator. I shall not use any black objects for insulation because black will radiate the heat greatly. I have found information from the internet, that the polystyrene will be the best in insulator.
I will have to bung up the end of the test tube as well because heat will be lost by convection currents. By keeping the test tubes well insulator the water molecules should be zooming around in the water at the same speed for a longer time with all that trapped heat energy.
I predict that polystyrene will be the best insulator against all the others. I think though it will result in the end being really close though and maybe another insulator will be better. The reason is polystyrene has a lot of trapped air in it, which will trap all that heat, plus it's a poor conductor and doesn't radiate heat through empty space. Though bubble wrap has lots of trapped air in the bubbles which makes it a good insulator. But my mind is still...