Officer Aptitude Rating (OAR) PracticeTest

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Study for the Officer Aptitude Rating Test with flashcards and multiple choice questions. Each question includes hints and explanations to help you understand your strengths and weaknesses. Prepare confidently for your exam!

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Which tool measures specific gravity using floats?

Hydrometer
Barometer
Thermometer
Altimeter

The correct answer is: Hydrometer

The tool that measures specific gravity using floats is the hydrometer. This instrument operates on the principle of buoyancy, where floating in a liquid allows it to gauge the liquid's density compared to water. The hydrometer consists of a sealed, calibrated tube with a weighted bottom that allows it to float upright in various liquids. When immersed, the level to which the hydrometer floats indicates the liquid’s specific gravity; liquids with lower densities allow the hydrometer to float higher, while denser liquids cause it to float lower. The other tools mentioned serve different purposes: a barometer measures atmospheric pressure, a thermometer gauges temperature, and an altimeter determines altitude based on pressure changes. Thus, they do not provide measurements related to specific gravity.