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: "Why would a swing go higher when two children push it at the same time?"

Answer: "There is more force acting on the swing"
Answer: yes

Problem: The mighty fane, with its three massive towers, rises majestically over the red roofs of the town. Its most striking feature is the great Norman screen, running up without buttresses or projections to the parapet and hiding the bases of the square, richly decorated towers of the west front. The plain centre of the screen is the work of Remigius, the first bishop. The rest of it is relieved with rich arcading of Late Norman and Early English periods. The wooden spires which crowned the towers were removed in 1807. In 1192 Hugh of Avalon determined to rebuild the Norman building of Remigius, which an earthquake had shaken. To him we owe the choir and eastern transept. His successors completed the western transept and began the west end of the nave. So much money had to be spent in rebuilding the central tower, which fell in 1239, that the canons could not rebuild the nave entirely, but had to incorporate the Norman end by Remigius. Unfortunately the axis of the west front does not correspond to that of the nave, which is too wide for its height. The low vaulting is a serious defect in the choir built by St. Hugh, but of the superb beauty of the Angel Choir, which encloses his shrine, there can be no doubt. In its richness of sculpture it is one of the masterpieces of Gothic architecture in England. The interior of the cathedral is remarkable for the harmony of its style, which is Lancet-Gothic, and the dim lighting of the nave only adds to its impressiveness.

Question: "Which building's spires were removed in 1807?"

Answer: "Norman building of Remigius"
Answer: yes

Problem: A handful of Bronze Age relics has fostered an assumption that prehistoric settlers inhabited Ibiza thousands of years ago. Greater evidence of such a people is found on Mallorca and Menorca than on Ibiza, but one of the Balearics' most important sites is actually on the island of Formentera, where the megalithic monument/tomb of Ca Na Costa has been dated to 2000 b.c. Ibiza's key location between Africa and ancient Iberia made it a convenient stopover for Mediterranean seafarers, such as the Phoenician traders, who called the island Ibosim. The Greeks dubbed it Ebysos, the Romans called it Ebusus, and the Moors, Yebisah. The Carthaginians: A detailed history of the island doesn't begin until it became a colony of Carthage in the 7th century b.c. . The Carthaginians originally came from the area comprising present-day Lebanon, and from their bases in North Africa and what's now Spain, they challenged the Roman Empire for domination of the Mediterranean region. Their interest in Ibiza lay partly in its vast salt flats, which to this day remain the source of a profitable industry. They capitalized on the natural resources by using the salt to cure fish, which they exported to their home country. The Carthaginians also carried out lead mining and continued to be of significance up until this century. It is believed that the lead pellets which were used by the Carthaginian general Hannibal were made on Ibiza. The Carthaginians also considered the island a holy place, and here in great splendour they buried thousands of their citizens in a huge necropolis on the Puig des Molins (Hill of the Windmills) below the Dalt Vila (Old Town) of Ibiza. Under the gnarled olive trees archaeologists have uncovered a treasure trove of statues, jewellery, pitchers, tools, and coins, which are now displayed in the town's two archaeological museums. The Romans never really infiltrated Ibiza, and even after the defeat of Hannibal in 202 b.c. during the Second Punic War their influence was restrained. Only with the fall of Carthage in 146 b.c. did they manage to make inroads, but, as local historians stress, Ibiza was neither conquered nor annexed by Rome, but confederated, retaining remarkable autonomy. For centuries to come the old Carthaginian traditions were allowed to continue on Ibiza alongside the new Roman way of life.

Question: "What did the Carthaginians want from Ibiza?"

Answer: "Salt"
Answer:
yes