An echo is heard when sound is reflected off a surface. Which of the following best explains this phenomenon? O A. Sound waves strike a barrier and then spread out radially toward an observer
O B. Sound waves travel from one medium to another, bend, and travel back toward an observer
C. Sound waves bounce off a barrier and then travel back toward an observer
OD. Sound waves are absorbed and reemitted by a barrier. Then, the waves travel
back to an observer.
Hel m pleas

No because scientist are still changing there mines today so they are not correct to this day

Answertraveling around a circular trackexplanation"traveling around a circular track" is the best answer as you could be traveling around a circular track at a constant speed. your velocity would therefore have the same magnitude but will always be constantly direction. since acceleration is the rate of change of velocity, the rate of change will only involve the direction of velocity and not the magnitude.wrong choices: "an object at rest" does not accelerate at all"increasing speed while traveling around a curve" means that the acceleration will not be constant due to only change in direction; it will be constant due to both magnitude and direction"an object in free fall" does not necessarily change direction 

What does the start look like