Wednesday, December 13

Spheres of Oil-A Science Fair Project

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Aim:

To demonstrate that gravity has little effect on bodies submerged in a liquid.

Materials:

Clear drinking water

1/2 cup rubbing alcohol

1/2 cup water

liquid cooking oil

eyedropper

Procedure:

Pour half cup of water into the glass

Tilt the glass and very slowly pour in half cup alcohol. Be careful not to shake the glass because the alcohol and the water will mix.

Fill the eye dropper with cooking oil.

Place the tip of the dropper below the surface of the top alcohol layer and squeeze several drops of oil.

Results:

The alcohol forms a layer on top of the water. The drops of oil form perfect spheres that float in the center below the alcohol and on top of the water.

Why?

Alcohol is lighter and will float on the water if two are combined very carefully. Shaking cause them to mix, forming one solution. The oil is heavier than alcohol, but lighter than water; thus the oil drops float between the two liquids.

Gravity does not affect the drops because they are surrounded by liquid molecules that are pulling equally on them in all directions. The oil molecules pull on each other, forming a shape that takes up the least surface area, a sphere.

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