SCIENCE with Ms Lun
Do oranges float or sink?
Objective
To show how the density of the orange changes when it is peeled
Materials
an orange
water
bucket
knife
kitchen scales (optional)
Difficulty:
Time: 5 mins
Adult supervision: to help peel the orange
Dangers: sharp knife
Instructions
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Half to three quarters fill the bucket with water.
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If you are using kitchen scales, weigh the orange & note the weight.
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Put the orange in the water. What happened? Your orange should've floated.
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Now carefully peel the orange. How much does it weigh now?
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Put the orange in the water. What happened? Your orange should've sunk.
The Science
My unpeeled orange weighed 210 g. Peeled, it weighed 164 g.
How can something heavier float and something lighter sink?
Think about what is in the skin & rind of the orange. There are tiny pockets of air in the rind and skin of the orange. This lowers the density of the orange compared to the water and the orange floats. When we peel the orange, we remove the air pockets. This increases the density of the orange compared to the water and the orange sinks. It has nothing to do with the weight of the orange, but rather its density.