Final answer:
A storage tank typically stores liquid fuel, and an oil level gauge is used to measure the fuel level. The storage principle involves both the physical matter and in some cases, such as a water tower, potential energy. The position of an oil tanker in water is determined by its overall weight when loaded.
Step-by-step explanation:
The storage tank mentioned in the question is designed to store a substance, and based on the given context, it most likely stores a liquid fuel such as gasoline or oil. The oil level gauge indicates the amount of fuel present inside the tank by measuring the voltage output of sender units, which is proportional to the volume of fuel.
In the case of a cylinder of gas, the storage would involve a compressible substance, typically in control of an adjustable piston. When the piston's volume is reduced, the pressure inside the tank increases, and vice versa for increasing volume. This principle is part of the gas laws that describe the relationship between the volume, pressure, and temperature of a gas. For larger storage systems like a water tower, it not only stores water but also the potential energy due to gravity that can be harnessed to move water without the need for pumps. Estimating the amount of water and energy stored requires knowledge of its volume and the height of the tower.
Lastly, the density of oil compared to water explains why an oil tanker sits lower in the water when loaded. Although the density of oil is less than water, the overall weight of the loaded tanker is more, causing it to displace more water and thus sit lower in the water.