Final answer:
A hydrometer, which operates on the principle of buoyancy, is used to measure specific gravity by floating in a liquid and providing a reading on a graduated scale. It is essential for checking the conditions of a car's radiator coolant and battery electrolyte for optimal performance and safety.
Step-by-step explanation:
Principle and Construction of a Hydrometer
The principle behind a hydrometer is based on the concept of buoyancy. The specific gravity measurement is accomplished as the hydrometer, which is a sealed hollow glass tube, partially submerges in the liquid, allowing the device to float at a level that corresponds to the liquid's density. The hydrometer consists of a weighted bottom for stability, usually filled with lead or mercury, and a narrow graduated stem where the specific gravity can be read directly from the scale at the fluid's surface level.
Purpose of Measuring Specific Gravities
Measuring the specific gravity of an automobile's radiator coolant and battery electrolyte is crucial for maintenance and safety. For the radiator coolant, it helps in determining the freezing and boiling points, ensuring the engine operates within the optimal temperature range. For the battery electrolyte, specific gravity readings can indicate the state of charge, with measurements revealing the concentration of the sulfuric acid, which is vital for the battery's proper functioning and lifespan.