Answer:
Waves interact with matter in several ways. The interactions occur when waves pass from one medium to another. Besides bouncing back like an echo, waves may bend or spread out when they strike a new medium. These three ways that waves may interact with matter are called reflection, refraction, and diffraction.
Explanation:
Answer:
OB) An elephant in the savannah develops without the ability to hear. A salamander living in a cave is born without, eyesight or fully developed eyes.
Explanation:
Adaptations are gradual modifications and changes in the physical characteristics or behavior of an organism, so that it could facilitate the survival of the organism in that particular environment.
In case of elephant without ability to hear specially in the regions of Savannah where there is vast grasslands with scanty vegetation and animals, then the elephant can't hear any sound of danger like approaching calamities, also it could hear the call of other elephants, in case if the elephant becomes segregated.
In salamander, low eyesight or low vision will further add to the misery, as there is already darkness in the cave. It could fall prey to any predator or it could not be able to feed on consumable organisms as it could see properly.
Given that,
The speed of a wave, v = 200 m/s
Wavelength, 
We need to find the frequency of this wave. The relation between wavelength, frequency and the speed is given by :

So, the frequency of this wave is 100 Hz.
Ecological succession is a process of inhabiting a zoological area by a group of organisms. it involves many stages to reach the climax stage such as primary, secondary, tertiary names basing on the habitat where it occurs. once the organisms reach the most stable stage of the succession. thus it maintains equilibrium
Succession helps restore the equilibrium of an ecosystem by forming up new species, diversifying species, and basically by replacing the damaged, deranged, or disturbed community. For instance, when a sudden climate change occurred in a community, such as drought, dryness, fire, or heat waves, all living things that depends on water or survives in a cool, wet environment will die or migrate somewhere else. Thus, leaving that community vacant and/or unoccupied by any living things. Succession, then, will take place in that area by going through various stages until reaching the climax stage, in which the ecosystem is complete again. c: hope i helped :D