Archimedes and the golden crown

One day in ancient Greece, King Hiero asked a crown maker to make him a golden crown. At first, he was very happy with it.

“It’s a nice crown, isn’t it?” he asked his men. Later, however, he began to doubt that it was a real golden crown. “Is it made completely of gold?” he wondered. He sent it to Archimedes and asked him to find out the truth.

“This problem seems difficult to solve. What should I do?” thought Archimedes.

Archimedes was still thinking about this problem as he filled his bath with water. When he got into the bath, some water ran over.

“That’s it!” shouted Archimedes. “I know how to solve the king’s problem!"

Archimedes went straight to the palace to see the king. First, he weighed the crown and asked the king for some gold of the same weight. 

Next, he put two pots into two big bowls and filled both pots with water. He put the gold into one pot, and some water ran into the bowl. Then he put the crown into the other pot. This time, even more water ran into the bowl.

“Look at this,” said Archimedes to King Hiero. “A crown made completely of gold displaces less water than a crown made of gold and another metal. This crown displace more water than gold of the same weight, so I’m certain that it’s not completely made of gold."

“The crown maker tricked me, didn’t he? What a bad man he is!” shouted King Hiero. He then sent the crown maker to prison.

 

Cao Chong weighs an elephant

Cao Chong was the son of Cao Cao.

One day,  Sun Quan sent Cao Cao a present. It was a huge elephant. Cao Cao wanted to find out the weight of the elephant.

“What a huge animal it is! Can anyone tell me how to weigh it?” he asked the crowd around him. 

“Can we get a large scale?” asked a soldier. However, no one could find a scale large enough.

“Can we cut it up?” asked another soldier. 

“No. I don’t want to kill it, “ said Cao Cao. Just then, young Cao Chong had a wonderful idea. “I can weigh the elephant!” he said.  “Let me have a try."

Cao Chong asked some soldiers to lead the elephant onto a boat. As the heavy animal walked onto it, the boat went lower into the water. Cao Chong drew a line on the side of the boat to mark how low it went. The elephant was then taken off the boat and the boat was filled with rocks until it went down again and water reached the line on the boat.

Cao Chong then weighed the rocks. He added up the weight of all the rocks and said, “This is the weight of the elephant."

Cao Cao was very happy with his son. “My son is very clever, isn’t he?” he said. Everyone agreed.