Why does the pitch of water going into a cup rise as the cup gets fuller?

Question

Why does the pitch of water going into a cup rise as the cup gets fuller?

In: 4

Answer 1

Turn a big bass drum so it’s facing downwards and hit the bottom. Then do the same with a smaller drum. The smaller drum will sound higher. The water going into the glass and hitting other water is like a drum that gets smaller as it fills up, making the noise higher.