Some species of moths have "developed a unique defence" characteristic of sounding like a bat and therefore fooling a bats sense of echolocation. what is this defence characteristic an example of?

What is friction? how does it affect the motion of an object?

An owl dives toward the ground with a constant velocity of 4.40 m/s at 53.0° below the horizontal. the sun is directly overhead and casts a shadow of the owl directly below it. what is the speed (in m/s) of its shadow on level ground?

Could we see a galaxy that is 20 billion light-years away?