Science Show Script

Science Show Script

Good morning/afternoon we are No Pressure Today we are going to be demonstrating the properties of air pressure and how these can do amazing things like pulling things like eggs into bottles and holding water in a bottle when it’s upside down.

Introduction to experiment: This experiment focuses on using the properties of air pressure to pull an egg into a chronicle flask without using force. Air pressure is the weight of the atmosphere pressing down on the earth.  

PERFORM EXPERIMENT

The science behind it: The science behind this experiment is that the burning match heats the molecules of air in the chronicle flask. This causes them to gain energy and then move far away from each other. Some of these molecules will escape from the flask around the egg that is resting on the neck of the flask (this is why the egg wriggles on the top of the flask). When the flame goes out, the molecules of air in the bottle cool down and lose energy causing them to move closer together (refer to powerpoint… these molecules on the screen are very active molecules that have so much energy from the fire that they have moved away from each other. But when the fire goes out because there is no more oxygen the molecules become less active and start to move closer together again). This is what scientists refer to as  a partial vacuum ( a partial vacuum is a term used to describe a volume of gas with a pressure lower than atmospheric pressure). Normally the air pressure outside the flask would come rushing to fill the flask, this is because the fire has used all of the oxygen that is available in the flask and needs more of the oxygen to sustain the fire . However, the egg is in the way and so it is pulled into the flask so that the air molecules outside the bottle can fill the flask with more air molecules.

So what do you think will happen to the egg when we put fire in the flask and an egg on top?

 My experiment is very similar. It shows how lighting a fire inside a container reduces the oxygen and other gasses in the jar, as fire fuels itself on oxygen. As the fire uses up the oxygen, if you block the surface with an object, say a balloon or egg-like Abby- the object will be suctioned in instead of the oxygen the fire is trying to get.

AFTER EXPERIMENT: The difference between my experiment and Abby is:

• The object being suctioned in.

But these are similar anyway, because of their elasticity. Elasticity is the ability of a solid to return to it’s original shape after the pressure causing the deformity is taken away. For example (doing this with a balloon) if I apply pressure to this balloon which has a remarkable amount of elasticity-more so than even the egg-it is deformed, meaning it has changed shape. However, once I remove the pressure, it reverts back into its original shape. This is because when there is external force, the object gains energy, and then reverts back to original low energy state, hence it is then less compact when there is no external force. Although balloons are elastic, there is a limit. This is called an elastic limit. When this limit is breached, often the object will start displaying plastic behaviour (becoming stiff and keeping to its deformed state) but in this case, the balloon will pop. Who wants to do the honours?