QUES: Sound waves are mechanical waves. They can travel only through matter. They cannot travel through empty space. This was demonstrated in the 1600s by a scientist named Robert Boyle. Boyle placed a ticking clock in a sealed glass jar. The clock could be heard ticking through the air and glass of the jar. Then Boyle pumped the air out of the jar. The clock was still running, but the ticking could not be heard. Thats because the sound couldnt travel without air particles to transfer the sound energy. Is there any other place where sound cannot be heard? Here is a hint: is there any other place that does not have air molecules? Thats right, in space sound cannot be transferred. So can astronauts hear each other? Yes, they can, because they are in enclosed space stations or pressurized suits.In both cases, they are surrounded by air molecules. If they left their space ship and did not use their electronics, they would not be able to hear each other. Next time you watch a science fiction movie, think about this factoid. When spaceships are destroyed by hostile alien beings, there would be no sound heard. Sound waves can travel through many kinds of matter.
Do you have any questions?
MY QUESTION: In a science fiction movie when aliens destroy a spaceship why would there be no sound heard?

QUES: Imagine you are standing in a farm field in central Illinois. The land is so flat you can see for miles and miles. On a clear day, you might see a grain silo 20 miles away. You might think to yourself, it sure is flat around here. If you drive one hundred miles to the south, the landscape changes. In southern Illinois, there are rolling hills. Why do you think this is? What could have caused these features? There are no big rivers that may have eroded and deposited this material. The ground is capable of supporting grass and trees, so wind erosion would not explain it. To answer the question, you need to go back 12,000 years. Around 12,000 years ago, a giant ice sheet covered much of the Midwest United States. Springfield, Illinois, was covered by over a mile of ice. Its hard to imagine a mile thick sheet of ice. The massive ice sheet, called a glacier, caused the features on the land you see today. Where did glaciers go? Where can you see them today? Glaciers are masses of flowing ice.
Do you have any questions?
MY QUESTION: What is the landscape in the Illinois farmlands?

QUES: The Glory of Melaka: In the early days, if you were not a pirate or a mosquito, Melaka was not much of a place to live. The land was infertile, just a swampy plain, the river small and sluggish. But it had a sheltered harbor, protected from the monsoons by neighboring Sumatra. Later, the strategic location and deep-water channel close to the coast brought in the bigger vessels of the trade-wind traffic crossing the Indian Ocean. The first to realize the larger commercial potential, as so often throughout the country's subsequent history, were the Chinese. In 1409, under a new directive from Emperor Chu Ti to pursue trade in the South Seas and the Indian Ocean, a Chinese fleet of 50 ships headed by Admiral Cheng Ho called in at Melaka. They made Parameswara an offer he could not refuse: port facilities and an annual financial tribute in exchange for Chinese protection against the marauding Thais. In 1411, Parameswara took the money to Beijing himself, and the emperor gratefully made him a vassal king. Twenty years later, the Chinese withdrew again from the South Seas trade. The new ruler of Melaka, Sri Maharajah, switched his allegiance to the Muslim trading fraternity by marrying into the Muslim faith, wedding the daughter of a sultan in Sumatra. Islam won its place in Malaya not by conquestas had been the case in North Africa and Europebut by trade, dynastic alliances, and peaceful preaching. Bengali peddlers had already brought the faith to the east coast. In Melaka and throughout the peninsula, Islam thrived as a strong, male-dominated religion of individuality, offering dynamic leadership and preaching brotherhood and self-relianceall qualities ideally suited to the coastal trade. At the same time, Sufi mystics synthesized Islamic teaching with local Malay traditions of animistic magic and charisma, though Islam did not become the state religion until Muzaffar Shah became sultan of Melaka (14461459). But the key figure in the sultanate was Tun Perak, bendahara (prime minister) and military commander. He expanded Melaka's power along the west coast and down to Singapore and the neighboring Bintan islands. He also had orang laut pirates patrolling the seas to extort tribute from passing ships. After Ailied district chiefs had repelled assaults from Thai-controlled armies from Pahang, Tun Perak personally led a famous victory over a Thai fleet off Batu Pahat in 1456.
Do you have any questions?
MY QUESTION: Why was Melaka not an ideal place for most people to live in its early days?

QUES: You might want to know how cold it is. You may need to know how fast the wind is blowing. Maybe it rained last night? Do you know how much? Does it feel humid to you? You have heard all these questions before. To answer these questions, we need data. That data comes from special tools. These tools collect data about the weather. You can see some of the common tools listed below: A thermometer measures temperature. An anemometer measures wind speed. A rain gauge measures the amount of rain. A hygrometer measures humidity. A wind vane shows wind direction. A snow gauge measures the amount of snow.
Do you have any questions?
MY QUESTION:
What tools are used to measure the amount of precipitation?