Determining the speed of an object without using light-based methods can be challenging, but there are alternative approaches available. Here are a few methods that can be used to measure speed without relying on light:
Radar: Radar is a commonly used method to determine the speed of objects. It relies on the principle of Doppler shift, which measures the change in frequency of electromagnetic waves reflected off a moving object. By analyzing the frequency shift, the speed of the object relative to the radar can be calculated accurately.
Sonar: Similar to radar, sonar uses sound waves instead of electromagnetic waves. By emitting sound pulses and measuring the time it takes for them to bounce back after hitting an object, the speed of the object can be determined using the Doppler effect.
Accelerometers: Accelerometers are devices that measure acceleration. By integrating the measured acceleration over time, the speed of an object can be determined. This method is commonly used in vehicles, smartphones, and other electronic devices to measure motion and speed.
Tachometer: A tachometer is a device used to measure the rotational speed of an object, such as an engine or a wheel. By converting the rotational speed to linear speed using the object's radius or diameter, the speed of the object can be estimated.
Inertial Navigation Systems: Inertial navigation systems use accelerometers and gyroscopes to track changes in velocity and orientation. By continuously measuring these changes and integrating them over time, the speed of an object can be determined. Inertial navigation systems are commonly used in aviation, maritime navigation, and space exploration.
Magnetometers: Magnetometers are used to measure changes in the magnetic field. They can be employed to determine the speed of conductive objects moving through a magnetic field, such as trains or vehicles equipped with magnetic sensors.
It's important to note that the accuracy and applicability of these methods may vary depending on the specific situation and the characteristics of the object being measured. Different methods are more suitable for different scenarios, and some methods may require calibration or combination with other techniques for improved accuracy.