TED-Ed: Why doesn't the Leaning Tower of Pisa fall over? | Alex Gendler

In 1990, engineers faced a crisis as Pisa's Leaning Tower was at risk of toppling. Historical construction errors and soil instability caused the tilt. Over centuries, various failed attempts were made to correct it. Modern engineers used computer models and new techniques to stabilize the tower, reducing its tilt to about 4 degrees. The tower now stands as a monument to engineering challenges and solutions, expected to remain stable for 300 years.

What was the critical angle at which the Leaning Tower of Pisa was projected to topple?

• 6.44 degrees

• 7.44 degrees

• 5.44 degrees

• 4.44 degrees

What was the primary reason for the initial tilt of the Leaning Tower of Pisa?

• Poor architectural design

• Inadequate foundation on marshy land

• Excessive height of the tower

• Use of substandard materials

Which architect attempted to compensate for the tower's tilt by adjusting the height of the floors?

• Filippo Brunelleschi

• Giovanni di Simone

• Leonardo da Vinci

• Michelangelo

What was one of the failed strategies used in the 19th century to address the tower's lean?

• Adding more floors

• Digging a walkway around the base

• Using steel cables

• Removing the bell chamber

What modern technique was used in the 1990s to stabilize the Leaning Tower of Pisa?

• Building a new foundation

• Removing soil from the north end

• Shortening the tower

• Adding more weight to the southern side