system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 Why do some metals ring when struck while others don't?
gpt
Depends on their stiffness. 

Any material,  plastic bag Vs a plastic bottle. A tight drum skin Vs a loose drum skin, will vibrate depending on its siffness. The stiffer the item the more it vibrates.

The shape of the item and how it relates to air makes the sound you hear. So a bell made of lead will ring louder than a ball of copper half buried in sand. Even though a copper bell is louder than a lead one.