The Leanign Tower of Pisa
Look at the picture! Nothing is wrong with your eyes. There is something wrong with the tower. It's the Leaning Tower of Pisa. It is in Pisa, a city in Italy.
In 1173, people in Pisa began to build the tower. They wanted it to be round and tall, taller than any tower in Italy. In 1178, when the tower was just three stories(层)tall, it began to lean. There was a war in Pisa at the time. So construction(建造) on the tower stopped for years. After about 200 years, in 1370, the construction was finished. The tower has eight stories. It is 55. 86 meters tall.
But why does it lean? There are different opinions about this. Some people have pointed out that while the tower is very tall and heavy, the ground(地面) is made of soft sand and clay(粘土). The tower leans because it is sinking(下沉) into the soft ground.
The tower is famous not only because of what it looks like, but also because of a famous experiment(实验). The great scientist Galileo did this experiment around 1590. He dropped(抛下) two iron balls from the top of the tower—one weighing 8kg and the other weighing 4 kg. Both balls landed(降落) on the ground at the same time. Most people thought the heavier ball would land first.
Leaning Tower of Pisa
Location(地点):
It is in Pisa, a city in .
History:
*People in Pisa wanted it to be round and .
*The tower was three stories tall in 1178.
*In 1370, it was stories tall.
Why does it lean?
*The tower is tall and , while the ground is made of and clay.
*It leans because it's sinking into the soft ground.
Ball experiment:
*Galileo did the experiment around .
*There were two different balls.
*The two balls landed on the ground at the .
