Rough surfaces create more friction than smooth surfaces. Thats why cars have tires. Its also why we use rubber mats in areas that might get wet. In your bathtub, you may even use No-Slip tape. No-slip is another way of saying the items has a lot of friction. In Figure 1.9, the blades of the skates are very smooth. Thats why you cant slide across ice with shoes. The soles of your shoes are much rougher than skates. The rougher surface of shoes causes more friction and slows you down. Heavier objects also have more friction. A heavy object presses down with more force. The surfaces are held together more tightly. This makes the surfaces harder to slide past each other. Did you ever try to push something heavy across the floor? Heavy objects are much harder to push than light objects.

Question: "When there is more friction, is it harder or easier to push an object across the floor?"

Answer: "Yes"

Response: yes

Earths magnetic field helps protect Earth and its organisms. It protects us from harmful particles given off by the sun. Most of the particles are attracted to the north and south magnetic poles. This is where Earths magnetic field is strongest. This is also where relatively few organisms live. Another benefit of Earths magnetic field is its use for navigation. People use compasses to detect Earths magnetic north pole. Knowing this helps them tell direction. Many animals have natural 'compasses' that work just as well. Birds like the garden warbler in Figure 1.36 use Earths magnetic field. They use it to guide their annual migrations. Recent research suggests that warblers and other migrating birds have structures in their eyes. These structures let them see Earths magnetic field as a visual pattern.

Question: "Name two benefits of Earths magnetic field."

Answer: "Helps protect Earth and its organisms. It protects us from harmful particles given off by the sun"

Response: yes

The French have always wanted to know what it means to be aFrenchman. Their history has been a constant quest for national identity: a conflict between strong regional loyalties and central authority. In about 2000b.c. Celtic tribes probably from eastern Europe came looking for greener pastures in the areas that are now Franche-Comte, Alsace, and Burgundy. At the same time, migrants from the Mediterranean countries were trickling into the south. The first recorded settlement was the trading post set up by Phocaean Greeks from Asia Minor at Massalia (Marseilles) around 600b.c. , followed by other ports at Hyeres, Antibes, and Nice. But the Greeks developed few contacts with the interior beyond a little commerce in olives and wine with the Celts of Burgundy. When their position was threatened by Ligurian pirates at sea and warlike tribes from inland, the merchants of Marseilles called on Rome for help. From Gaul to France In 125b.c. , the Romans came in force, conquered the "Gallic barbarians," and set up a fortress at Aquae Sextiae (Aix-en-Provence). They took advantage of this new stronghold to create Provincia (now Provence), stretching from the Alps to the Pyrenees, in order to guarantee communications between Italy and Spain. When this province was endangered by fresh attacks from the north, Julius Caesar himself took charge, conquering practically the whole of Gaul by 50b.c. Caesar drew Gaul's northeastern frontier at the Rhine, taking in present-day Belgium, and warned that the Germanic tribes across the river the Franks (after whom France is named), Alamans, and Saxons would always threaten the security of the frontier. The Romanization of Gaul sent the most energetic warriors to defend the outposts of the empire while their families settled down to work the land or build towns such as Lyon, Orange, Arles, and Nimes, and the first great highways between them. At the same time, merchants built up a thriving trade with the rest of the Roman Empire. The pattern for the peasantry and bourgeoisie of France was thus established. Christianity was introduced into Gaul in the first century a.d.

Question: "What was happening in France in about 2000 BC?"

Answer: "Celtic tribes came in"

Response: yes

Light rays strike a reflecting surface. They are then reflected back. You can predict the angle of the reflected light. Imagine a ball bouncing off a surface. Light can do the same thing. That is, assuming the surface is shiny. So how do you know where light will go after it strikes a shiny surface? It depends on how the light initially strikes the shiny object. Light does not always go straight toward a surface. Therefore, not all light bounces straight back. Sometimes, light can hit a surface at an angle. The angle at which it strikes the surface tells us how it will bounce off. While light is different to a ball, they react in a similar manner. Many sports rely on knowledge of reflection. Pool players know a lot about reflection. They take great care when they strike the pool ball. They need it to go to a certain place. They know the angle it will hit the side of the pool table.

Question: "What has to be true in order to use a knowledge of reflection to help in sports?"

Answer: "The knowledge of friction could help."

Response:
no