Inflate a balloon *inside* a bottle
One of the basic physics principles is that heat causes things to expand (get bigger) and cold causes things to contract (get smaller). Things such as air will contract and take up less room when cooled. Similarly, things will expand when they get hot.
- Fill the bottle with hot water.
- Fill the bowl with cold water.
- Let both sit for one minute. Then empty out the bottle.
- Stretch a balloon over the mouth of the bottle.
- Set the bottle in the bowl of cold water.
The warm water heats the bottle. When the water is poured out, the heated bottle then heats the air inside of it. When the bottle is placed in the cold water, the air inside the bottle cools and contracts (gets smaller and takes up less room), causing outside air to be drawn in, pulling the balloon in and inflating it inside the bottle.
Magical inflating balloons experiment advanced notes – thermal expansion
Thermal expansion refers to the tendency of matter to change in volume, length or area in response to changes in temperature. Most solids and liquids expand when they are heated and contract when they are cooled. Gases also expand when they are heated at a constant pressure. If a gas is heated in a container that prevents expansion, the pressure of the gas increases.
When an object absorbs heat, its particles start to vibrate and move more quickly, causing them to take up more space and push against the surrounding particles. This increase in particle movement results in an expansion of the object.
The degree of thermal expansion depends on the material’s coefficient of thermal expansion (CTE), which varies from one substance to another. Some materials expand more than others when heated, and some actually contract upon heating. For example, metals typically expand when heated, while rubber contracts.
Thermal expansion can have significant implications in engineering, construction, and manufacturing. If not properly accounted for, thermal expansion can cause stress and damage to structures, equipment, and devices.
But what about negative thermal expansion?
Negative thermal expansion, also known as negative coefficient of thermal expansion, is a phenomenon in which a material shrinks in size when its temperature is increased. This is in contrast to the more common behavior of materials expanding when heated.
The reason behind negative thermal expansion is related to the molecular structure of the material. When a material is heated, the molecules in the material start to vibrate and move around more, which usually leads to an increase in size. However, in materials with negative thermal expansion, the molecular structure is such that the movements of the molecules cancel each other out, resulting in a net decrease in size.
One example of a material with negative thermal expansion is quartz. As the temperature of quartz increases, its molecular structure causes the bonds between the atoms to become more rigid, leading to a decrease in size. Another example is zirconium tungstate, which has a unique structure that allows it to contract along one axis while expanding along another.
Supplies required for the Magical inflating balloons experiment
Supplies: Plastic bottle, Balloon, Plastic bowl
Image Credits
In-Article Image Credits
Flying Cathedral hot air balloon via Wikimedia Commons by Bohringer Friedrich with usage type - Creative Commons License. July 6, 2009Featured Image Credit
Flying Cathedral hot air balloon via Wikimedia Commons by Bohringer Friedrich with usage type - Creative Commons License. July 6, 2009
