Brain Teasers
Buoyancy
Science
Science brain teasers require understanding of the physical or biological world and the laws that govern it.Science
Suppose you have a rubber ball 1 foot in diameter, and a latex balloon filled with helium until it is 6 inches in diameter.
Which has a greater buoyancy force?
Which has a greater buoyancy force?
Hint
Look at the formula for buoyancy force. Something people should think is in it is not.Answer
The rubber ball. This seems to contradict what you think, so let me explain.The formula for buoyancy force is:
Buoyancy Force = Fluid Density * Object Volume * Gravity
As you can see, buoyancy force has nothing to do with the density of an object, just the volume, so since the ball takes up more space then the balloon, it has a greater buoyancy force.
But, you may object, then why does the ball sink and the balloon float? Well, again, the density of the object has nothing to do with buoyancy, so even though the balloon has less buoyancy force, it floats because the force from gravity is even less.
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