Question

Using a reliable source, find out how much tension do the strings of a piano have. Using this, explain why pianos had to wait until the development of cast iron before the first piano was created.

Answer 1

It is a know fact that piano string generate a lot of force ( tension) when played that a simple weak body will break apart under this force. To give you an idea, just know that 230 metal strings in a piano add up to around 250 kN of force. That's a huge force.

This is the reason why we need frames like cast iron frame to support this load from strings. This is also the reason why Pianos are big, heavy. Most of the weight of modern Piano can be attributed to cast iron frame.