Question

Which statement is true of a mechanical wave?

Both sound and light are examples.
It must have a medium.
It can travel in a vacuum.
It must travel in empty space.


When traveling from a solid to air, what would a sound wave be expected to do?

stay the same speed
fluctuate speed
slow down
speed up


Why does a siren have a higher pitch as it approaches you?

The troughs of the sound wave are farther apart.
The period of the sound wave is increased.
The crests of the sound wave are spaced closer together.
The amplitude of the sound wave is increased.