Problem: Over the centuries, the living here has always been easy enough to attract a steady stream of immigrants. Bountiful food sources might have made Malaysia an inviting place for the contemporaries of Java Manin 230,000 b.c. But thus far, the country's earliest traces of homo sapiens, found in the Niah Caves of northern Sarawak, are fragments of a skull dating to 40,000 b.c. On the peninsula, the oldest human-related relics (10,000 b.c. ) are Stone Age tools of the Negritos. These small, dark Melanesians are related in type to Australian aborigines and are confined today to the forests of the northern highlands. By 2,000 b.c. , these timid, gentle nomads hunting with bow and arrow were driven back from the coasts by waves of sturdy immigrants arriving in outrigger canoes equipped with sails. Mongolians from South China and Polynesian and Malay peoples from the Philippines and the Indonesian islands settled along the rivers of the peninsula and northern Borneo. They practiced a slash-and-burn agriculture of yams and millet, a technique that exhausted the soil and imposed a semi-nomadic existence from one jungle clearing to another. Families lived in wooden longhouses like those still to be seen today among the Iban peoples of Sarawak. Another unit was added on to the communal dwelling each time a marriage created a new family. Other tough migrants from the South Seas settled along the coastssailors, fishermen, traders (for the most part pirates)known euphemistically as orang laut (sea people).

Question: "What did the Mongolians and Malay do to the Negritos?"

Answer: "They drove them back when they landed on the shores"
Answer: yes

Problem: When land is cleared, habitats are lost. It may be cleared for agriculture. It may also be used for building new homes or businesses. Within the past 100 years, the amount of land used for agriculture has almost doubled. Land used for grazing cattle has more than doubled. Many wetlands have also been lost to agriculture. The U.S. has lost almost all the natural tall-grass prairies. Thee areas of tall thick grass have virtually disappeared. These areas of land had thick fertile soil. Their grasses had very deep root systems. These deep and thick roots reduced the amount of soil erosion. They also were home to many plants and animals. Prairies were wonderful places. They were home to colorful flowers, prairie dogs, and herds of bison.

Question: "In the last 100 years, how much has the agricultural clearing grown and how is it used?"

Answer: "Doubled"
Answer: yes

Problem: What if two children push a swing at the same time? Would the swing go higher? Yes, together their force would be more. It is common for forces to be combined. Most objects on Earth have at least two forces acting on them. Do you know what one of them is? Of course, that force is gravity. How many forces do you have on you right now? Gravity pulls you down toward the center of Earth. Your legs exert a downward force. They hold you up against the pull of gravity. Consider the example in Figure 1.3. A book is resting on a table. Gravity pulls the book downward. It has a force of 20 newtons. At the same time, the table pushes the book upward. Its force is also 20 newtons. The table opposes the pull of gravity.

Question: "How many forces do you have on you right now?"

Answer: "3"
Answer:
no