An anemometer is a meteorological instrument used to measure which of the following physical quantities?

Introduction / Context:

This question is about identifying the correct use of an anemometer, a common instrument in meteorology. Weather stations and climate studies require accurate measurements of wind speed to forecast weather, study storms, and design buildings that can withstand strong winds. Knowing which quantity an anemometer measures is basic environmental physics knowledge.

Given Data / Assumptions:

• The instrument named is an anemometer.
• Options list speeds of light, wind, water current, and satellites.
• We assume standard meteorological equipment definitions.
• We are concerned with the primary, textbook use of this instrument.

Concept / Approach:

An anemometer is specifically designed to measure wind speed and sometimes wind direction. Classic cup anemometers have rotating cups that spin faster when winds are stronger, and the rotational speed is converted into a wind speed reading. Other types include vane anemometers with propeller blades. None of these instruments are used to measure speed of light, water currents or satellite motion in space. Thus, the correct answer is speed of wind.

Step-by-Step Solution:

Verification / Alternative check:

Illustrations in geography and physics textbooks show anemometers mounted on masts alongside wind vanes. Weather reports often quote wind speeds measured in kilometres per hour or knots, derived from anemometer data. No serious scientific source associates anemometers with measuring speed of light or orbital velocities. This consistent usage confirms that the proper association is with wind speed.

Why Other Options Are Wrong:

• Speed of light: Determined by optical and electromagnetic experiments, not by rotating cups or vanes in air.
• Speed of water current: Measured in rivers or oceans using current meters or flow sensors, different devices from anemometers.
• Speed of satellites: Calculated using orbital parameters and space tracking systems, not simple surface wind instruments.

Common Pitfalls:

Because the term anemometer may not be familiar, students sometimes guess based on sound and may link it to any kind of speed. The key hint is its frequent appearance in weather station pictures. Remember that anemos is related to wind in Greek, which can help you associate anemometer with wind measurement. Connecting instrument names to their typical context is a good strategy for such questions.

Final Answer:

An anemometer is used to measure the speed of wind.