In: Physics
An object has a measured volume of 800 cm3. It is tied to a string and fully submerged in water (density of water = 1000kgm3). The string exerts an upward force of 15.0N to keep the object still.
Calculate the density of the object.
There are three forces acting on the object: mg is the gravitational force of the earth, FB is the buoyant force of the water, and T is the tension in the string. The free-body diagram of the object is shown below:
The object is kept still, the net force on the object is zero
Let
and
be the density of the water and the object respectively, The
volume of the object is
The mass of the object is
The buoyant force is equal to the weight of the water displaced by the object.
Substituting in (1)
Substituting
we get