The speed of a mechanical wave through a medium depends on the type of medium. it also depends on the type of mechanical wave. which statement is true?

all waves travel at the same speed if no medium is present.

electromagnetic waves require a medium, but mechanical waves do not.

all waves travel at the same speed through any medium.

mechanical waves require a medium, but electromagnetic waves do not.

What the theory that the sun goes around earth was replaced with the theory that earth goes around the sun this was an exaple of a

Research cheetahs on the internet what has contributed to this animal becoming "endangered" or "threatened." what animal you have chosen? -cheetah how long has the animal been endangered or threatened? what has contributed to this animal’s endangered or threatened status? why is it important to save this animal from extinction? after researching and gathering facts, write a 350-word letter from the point of view of an animal rights' activist. be sure to include at least five facts that you learned from your research.

Why is the theory of evolution important? it disproves all other theories about how life began. it provides a topic for debate. it is a unifying concept in biology. it explains how life began. i know for sure, it is not "it is a unifying concept in biology."