Density, Specific Gravity, and Viscosity - College Physics
Card 0 of 2
The reason why a coconut floats in water is because __________.
The reason why a coconut floats in water is because __________.
The equation for the buoyant force is 
. The gravitational force is constant. In order for the coconut to float, the buoyant force must be greater than the gravitational force. If the gravitational force is greater than the buoyant force, then the object will sink.
The equation for the buoyant force is
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A baseball has a mass of 
, but it weighs 
when completely submerged in water. What is its volume assuming that the density of water is 
?
A baseball has a mass of
We are given the mass of the baseball outside of the water. Using the weight equation 
with the gravitational constant being 
and the mass being 
, the weight of the baseball outside of the water is 4.905 N. (Be careful and convert the mass of the baseball from grams to kilograms since we are using SI units).
The buoyancy force is the difference of the weight of the baseball when it is in the air and when it is in the water. So subtract the two differences:
Now we use the buoyancy equation:
where 
is the buoyancy force, 
is the density of water, 
is the volume of the baseball, and 
is the gravitational constant. Plug in the known variables and solve for the volume.
and we get 
We are given the mass of the baseball outside of the water. Using the weight equation
The buoyancy force is the difference of the weight of the baseball when it is in the air and when it is in the water. So subtract the two differences:
Now we use the buoyancy equation:
and we get
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