Answer:
**[D] Sound waves**
Sound waves can be used to measure the speed of an approaching car using the Doppler effect. The Doppler effect causes a change in the frequency (and thus pitch) of sound waves in relation to the observer and the source of the sound when they are moving relative to each other. By analyzing the change in frequency of the sound waves emitted by the car, you can determine the car's speed.
While light waves, microwaves, and radio waves can also be used to measure speed, they are not typically used for measuring the speed of approaching vehicles in everyday applications. For example, radar guns use radio waves to measure speed, and lidar systems use light waves, but in the context of sound waves, the Doppler effect is a direct and practical method.
Explanation:
Answer:
[C] Radio waves
Explanation:
Radio waves are used in radar to determine the speed of an incoming car The radar picks up the waves reflected off of the car and because of the Doppler effect, from the changing of frequency of the waves, the system can figure out the speed of the car.
Therefore, the correct answer is [C].