Which instrument is specifically designed for measuring the amount of work performed by a person or a machine, and is commonly used in exercise physiology and ergonomics?

Introduction / Context:

Scientific instruments often have similar sounding names but measure very different quantities. In competitive exams, questions frequently ask you to match instruments with the physical quantities they measure. This question focuses on the instrument used to measure work performed, especially in contexts such as exercise testing and ergonomics, where the mechanical work done by muscles is of interest.

Given Data / Assumptions:

• We are dealing with instruments used in physics and related sciences.
• Work in physics is defined as force applied over a distance in the direction of motion.
• The correct instrument directly measures or quantifies work done.
• Other instruments in the options measure different physical quantities such as wind speed, rainfall or gas volume.

Concept / Approach:

An ergometer is an instrument designed to measure the work performed by a person or a machine. The name comes from erg, an older unit of work or energy in the CGS system. In modern settings, ergometers are used in laboratories and gyms to test physical fitness, such as cycle ergometers and rowing ergometers that measure power output and total work done during exercise. Eudiometers, anemometers and hyetometers are unrelated to mechanical work and are used for gas volume, wind speed and rainfall measurement respectively. A dynamometer measures force or torque, not the total work done directly, although it can be used to compute work if displacement is known.

Step-by-Step Solution:

Verification / Alternative check:

Textbooks and fitness testing protocols frequently refer to cycle ergometers, which are specialised stationary bicycles connected to devices that measure the work done by the subject over time. The data are expressed as power (watts) and total work (joules), both derived from the mechanical work performed. This confirms that ergometers are directly associated with measuring work. In contrast, anemometers are always mentioned in the context of wind, and hyetometers in the context of rainfall, making them clearly unrelated to mechanical work measurement.

Why Other Options Are Wrong:

Option A (eudiometer): Used in gas analysis, especially in laboratory setups to measure the volume of gases involved in chemical reactions.

Option B (anemometer): Measures the speed of wind and is installed on weather stations and wind farms.

Option C (hyetometer): Measures the amount of rainfall over a period and is used in climatology and hydrology.

Option E (dynamometer): Measures force or torque; while related to mechanics, it does not directly measure work, which requires knowledge of both force and displacement.

Common Pitfalls:

Students often confuse ergometer with dynamometer because both are used in mechanical and physiological testing. The key difference is that dynamometers focus on force or torque, whereas ergometers focus on total work or power over time. Remember the root erg in ergometer, which hints at energy and work, helping you to choose the correct instrument in exam questions.

Final Answer:

The instrument for measuring work performed is called an ergometer.