Final answer:
Radar detects objects by using the reflection of radio waves and measures object speed using the Doppler effect.
Step-by-step explanation:
The behavior of waves utilized by radar to detect the presence of objects is the reflection of radio waves. Radar systems transmit radio waves which then reflect off of objects and return to the radar system. By analyzing these echoes, it is possible to determine the object's distance, speed, and other characteristics. In addition, the Doppler effect is employed to measure the speed of objects; moving objects induce a change in frequency of the reflected waves, which can be detected and quantified. This principle is also applied in astronomy to determine the movement of stars and galaxies.