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

Astudent wears sunglasses to her read a book more easily which wave interaction occurs as light passes from the air into the plastic lenses? a polarization b.refraction c.diffraction d. interference

What properties of a moving object are used in determining the object's energy of motion

Arunner is jogging at a steady 3.6 km/hr. when the runner is 2.9 km from the finish line, a bird begins flying from the runner to the finish line at 14.4 km/hr (4 times as fast as the runner). when the bird reaches the finish line, it turns around and flies back to the runner. even though the bird is a dodo, we will assume that it occupies only one point in space, i.e., a zero-length bird. how far does the bird travel? (b) after this first encounter, the bird then turns around and flies from the runner back to the finish line, turns around again and flies back to the runner. the bird repeats the back and forth trips until the runner reaches the finish line. how far does the bird travel from the beginning? (i.e. include the distance traveled to the first encounter)