Experiment
Balloon on a skewer
Curriculum objectives - Science:
- explore and describe observable properties of various objects, materials and substances and sort by properties
You need:
- A balloon
- A knitting needle
This is what you do:
Blås opp en ballong til omtrent halv størrelse.
Stikk en et lite hull i enden av ballongen der plasten er tykkest. Hvis strikkepinnen er for tykk kan du bruke en liten nål og raskt stikke strikkepinnen inn i hullet.
Stikk strikkepinnen gjennom hele ballongen og ut igjen ved siden av knuten.
Klarer du det uten at ballongen sprekker?
Observe and explore:
- Try with more pins.
- Experiment with smaller and larger balloons.
- How many balloons can you fit on a stick?
Record your observations.
Å skyve et spyd gjennom midt på ballongen er umulig med mindre du har litt teip.
Legg et lite stykke klar tape midt på ballongen. Plasser spissets skarpe punkt midt på båndet og skyv spydens ende forsiktig inn i ballongen uten å sprekke den!
Prøv det igjen, men andre enden av balongen.
What is going on?
This experiment shows the strength properties of the rubber used in the balloon. Latex rubber is extremely elastic but has very little strength.
Rubber is made of many long threads or chains of molecules. These long strands of molecules are called polymers, and the elasticity of these polymer chains causes rubber to stretch. When the balloon is inflated, these strands of polymer chains stretch, particularly in the center of the balloon.
Balloons are also made with thicker top and bottom materials. The long strings of molecules stretched around the spear and hold the air inside the balloon. The extra thickness of latex rubber and the elasticity means that you can stick a stick in the balloon without bursting it.
The secret to making this experiment work is to use the part of the balloon where the rubber molecules are under the least possible strain.
