How To Make Hot Air Balloon

Level Primary, Elementary

Concept

The gas inflates when it is heated. Let's make easy balloon by using this phenomenon.

Materials

garbage bag (thin, big one is good), enameled wire, tissue paper, sprit, adhesive tape, and match.

Fabrication

(1)The enameled wire is put on surroundings of the garbage bag with the adhesive tape.  
(2)Other enameled wires are put in four places as shown in figure.  
(3)Tissue paper is held to  the centre of wire and put sprit a little.  
(4)Top of the bag is held and the tissue paper is put on fire. Be careful not to fire the bag.  
(5)The bag inflates and goes up.

Precaution

This experiment doesn't succeed at temperature high, summer time. Winter when the temperature is low is the best.   Please do in the windless place.

Science

This experiment is simple. But students can make sure three phenomena when they
think why the balloon can go up in the air.

1. The movement of the gas molecules become faster at the high temperature. So the volume of gas grows. It is Charles' Law. Students can see the garbage bag inflation.

2. When the volume of the gas grows, the mass for each unit volume becomes small and the density becomes small.

3. Buoyancy of gas inside the bag beco

mes more than gravity when the density of in it is smaller than that of surrounding gas. And the balloon goes up.

Application

The bag goes up for a while even if w

arm air is sent to the inside with the hair drier instead of using the fire.