What is the purpose of a tachometer in a mechanical system?

The purpose of a tachometer in a mechanical system is to measure speed, typically the rotational speed of an object such as an engine or a shaft. This instrument provides critical information that helps in monitoring and controlling the operation of machinery. By displaying the speed of rotation, the tachometer allows operators to ensure that equipment runs within specified limits, preventing mechanical failures or inefficiencies.

In various industrial applications, knowing the speed of machinery is essential for tuning performance, optimizing operations, and ensuring safety protocols are met. For instance, in engines, if the tachometer indicates that the engine is running too fast, adjustments can be made to avoid potential damage.

The other options focus on measuring different parameters — pressure, temperature, and flow rate — which are not functions of a tachometer. Each of these has its respective instruments designed specifically for those measurements, highlighting the specialized role of the tachometer in assessing rotational speed.