Which instrument is specifically designed for measuring speed?

The speedometer is specifically designed to measure the speed of a vehicle. It provides real-time information about how fast the vehicle is traveling at any given moment. This instrument works by calculating the rotational speed of the wheels and translating that information into a speed reading displayed on the dial or digital screen.

In contrast, a tachometer measures the engine speed, typically expressed in revolutions per minute (RPM), which is important for understanding how hard the engine is working but does not directly indicate the vehicle's speed relative to the road. An odometer records the total distance traveled by the vehicle over time, which is useful for maintenance and service intervals but does not provide speed information. An altimeter measures altitude and is used in aviation or mountaineering rather than determining speed. Each of these instruments serves a specific purpose, but the speedometer is uniquely designed to provide speed readings.