As you have seen in this lab, the density of water is near 1 g/cm3. Anything with a density lower than this will float in water,
and anything with a higher density will sink. Imagine you are building a submarine. How could you be sure to have it sink and then rise? Make sure its density is always above 1.0 g/cm3.
Make sure its density is always below 1.0 g/cm3.
Develop a way to adjust its density so that it can be above and below 1.0 g/cm3.
The third answer is the one you want. You have to have an adjustable density. All other things being equal, if the tanks you use for holding just water when filled with water will let the sub sink, because the sub is made of a dense metal like iron or steel.
If on the other hand you fill these tanks with air, the net density will be below one and the sub will rise.
Answer: C) develop a way to adjust its density so that it can be above and below 1.0 gram per cubic centimeter.
Explanation: Submarine is a kind of special ship that can float above and below water. We know that an object can only float over water when its density is less than the density of water and it would sink if its density is greater than the density of water.
A submarine has tanks in which water is filled if we want to sink it and the water from the tanks is taken out with the help of water pumps to rise the submarine. These water tanks in the submarine helps to adjust its density.
The over all density is increased by filling the water tanks to sink the submarine and the density is decreased by removing the water from the tanks to rise the submarine.
