Raingutter Boat Racing - | Breathing Life Into Your Boat |
Archimedes also discovered another curious fact about the property of objects called "density". When a less dense object is placed inside a more dense liquid, it floats. This reaction of the less dense object is called buoyancy.
By studying buoyancy in water via floating and measuring many objects, Archimedes discovered that the weight of a floating object is the same as the weight of the water moved aside by it. So if we know how much a cubic inch of water weighs (its weight-density), we can weigh almost anything by making it float and we can measure its volume by submersion. The weight divided by the volume is the object's density.
Unit | Weight (oz) |
gallon | 128 |
half gallon | 64 |
quart | 32 |
pint | 16 |
cup | 8 |
tablespoon | 1/2 |
teaspoon | 1/16 |
Can you tell by looking at the picture which is more dense, pine or balsa? Both boats pictured weigh 2 ounces. Both boats displace the same volume and weight of water. But pine is about three times more dense than balsa.
Unit | Volume (in3) |
gallon | 230.9 |
half gallon | 115.5 |
quart | 57.7 |
pint | 28.9 |
cup | 14.4 |
tablespoon | 0.9 |
teaspoon | 0.11 |
Note: density is usually measured in terms of mass per unit volume. That's why I sometimes use the wording "weight-density". It means the density is in terms of weight per unit volume which is often more convenient to compute.
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Raingutter Boat Racing - | Breathing Life Into Your Boat |
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