Orange Surprise (Sink or Float: Peeled Vs. Unpeeled)

Good evening scientists! We have an easy experiment that you can do with any citrus fruit that you can peel. We choose to use a tangerine (Orange to my little scientist), he named the experiment after we did it.

Materials

Orange Surprise (4)

2 Tangerines, Oranges, or Grapefruit

Tall, Clear Vase

Water

Investigation

  1. Fill your vase with water and set aside. Peel one of your fruits. Make sure to get the entire peal off.Orange Surprise (7)
  2. Place one of the fruits into the vase, note if it sinks or floats. My little scientist wanted to try the peeled fruit first.Orange Surprise (24)
  3. Place the other fruit into the vase, again noting if it sinks or floats.Orange Surprise (25)

Talking Points

The fruit with the peel floated and the fruit that we had peeled sank. Why did this happen? The secret is the pits in the fruit’s peel or rind. When you look closely at your fruit you will see little pits or dimples, these allow the peel to be porous allowing air into the orange. The peel allows the fruit to trap little air pockets in the rind causing the fruit to be less dense the water, allowing it to float. When you remove the rind by peeling the fruit you allow remove the tiny air pockets, thus causing the fruit to sink because it is more dense than water.

Density is calculated by looking at the mass (How there is of something) and dividing it by the volume (how much space it takes up). The orange with the peel has a greater volume then the peeled orange. The density of the orange with a peel is less then the orange that was peeled.

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