Introduction
Welcome! I hope you are ready for a wild ride. You will go above, below, into, and around the earth. Hold on tight as the forces take us away.
Task
Through our study of forces we have learned that a force is a push or pull that can cause movement. We have also discovered that there are many different types of forces, and many things that can cause forces.
Today you will read about forces caused by nature, and how human actions can change the effects that nature's forces cause.
To start, click on each of the four topics on the side menu. Read through the information there and look at the pictures. When you are complete click on "Assignment" on the side menu. Then, follow the instructions given to you there.
Good luck, and have fun.
Process
| Erosion - | When gravity causes water to flow downwards. As the water flows soil and rocks are moved with it. |
| Heavy rains and water run-off (water flowing off the land) naturally erode soil. Humans make erosion happen faster by cutting down trees, removing shrubs and plants, and having too many animals on farmland. | |
 When soil is lost through erosion, it pollutes rivers, lakes and other water systems. It also changes the land. The picture to the left shows a channel that has been formed by flowing water.
The loss of soil can cause plants to become uprooted, meaning they can no longer live. When soil is lost on farmlands, farmers cannot grow as many crops. Depleted soil produces crops that provide less nourishment to people. |
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| Erosion effects the human environment by more than affecting our food supply. When land is eroded it can effect structures as well. The picture below shows a building being torn down. The reason it is being torn down is that it was located near a beach, and the sand has slowly been washed away, which caused the building to be unstable (if you want to read more about this, here is the news story).
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 To try to stop the erosion of land, humans will often put up walls or other barriers to stop the water from touching the soil. They also use pipes to redirect the water to a place where it will not affect the land as much. In some cases, like the picture to the right, this helps keep us safe
Humans have also taken advantage of the flowing water that causes erosion. By directing the water they can capture the energy from it to power other things. This water wheel is being turned by water that has been direct through a man-made channel.
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Landslide - |
When gravity causes a large section of land to slide downward across other land. |
| Landslides can happen anywhere and are triggered by rains, floods, earthquakes, and other natural events. Humans contribute to landslides when they change the land to put in lawns, gardens, roads, and houses. | |
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When landslides occur they can cause flooding and can pollute water. They can carry trees and plants away with them. All of the movement of rock, vegetation, and other objects can cause a drastic change in the landscape. The image below shows a section of land from which all of the plant life has been removed and pushed down into a river. When large sections of land are removed there are animals who are left homeless, and unfortunately many are also caught up in the slide and do not survive. |
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 Landslides can destroy houses, transportation routes, and utilities. In fact, there is so much energy in a landslide, that there is not much that can stop one. The picture to the right shows a city that has had dozens of house completely eliminated. As you will see in the video at the bottom of this page, it does not take long for this to happen. Even a small landslide can destroy a road or a train track in seconds. When a landslide occurs, people can be without electricity or water for weeks. Experts are saying that global warming will increase the number of landslides, you can read about it here. |
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 Unfortunately there is not much good that comes from a landslide. Also, they are so powerful that there is nothing that can be done to stop one once it has started. To try to reduce the impact of a landslide humans use technology to research and learn about the land. It is also a good idea not to change the land, it should be left as is. One thing that is done to attempt to control minor landslides is the use of wire fences. |
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Lightning |
A release of electricity from the atmosphere, seen as a bright line and normally accompanied by thunder. |
| Lightning occurs when there is too much electric charge in the sky. It is released and all the energy is transferred to the earth. Humans do not contribute to the effects of lightning, but global warming could lead to an increase in the amount of lightning. | |
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Lightning can also start forest fires, which cause far more destruction than the lightning itself. In fact 42% of forest fires are caused by lighting (the other 58% by humans). That fact was taken from this article. |
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 The effects lightning have on the human world are very similar to the effects it has on nature. The house shown in this picture was struck by lightning, which caused it to catch on fire. Just like lightning is drawn to taller objects, it is also drawn to metal. there have been many times when people have been hit by lightning while they were golfing, or carrying a metal umbrella. Other things like hydro poles and fences are also targets for lightning, which can cause large scale power failures if it strikes the wrong place. |
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| Humans have learned a lot about lightning, and in doing so they have made several "rules" about handling it. Never stand under a tree in a lightning storm, don't hold metal objects or never step out of a car that has been hit by lightning. Several buildings are also equipped with lightning rods, metal poles that are meant to be hit by lightning (picture below). The energy is carried down the pole, and safely to the ground. Unfortunately, at this time, there is no way to collect that energy because it is too quick and powerful.
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When lightning strikes the earth it can be devastating. Lightning will normally strike taller objects, and therefore often strikes trees. The picture to the right shows a tree that has been hit. When this happens the tree dies, and also animals who make their home in the tree lose that home. 
| Tidal Wave - | A large gathering of water that is forced into a small area, creating a large wave. |
| A tidal wave is caused by shifting of the ground under the ocean, and can be very dangerous to things around the water's edge. Drilling for oil and removal of large sections of land are two things humans have done that can affect the formation of these waves. | |
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The land that gets taken under the tidal wave can also be destroyed, so that it can no longer support plants. The picture to the right shows land that would have once been used to support farms and other plant life. All of this is now gone. Also, marine life is greatly affected. All of the things that are dragged back into the water can become a problem for marine life, not to mention the marine animals who get trapped on land when the water retreats. |
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 Humans can have their homes and businesses taken away by a tidal wave. When things are built too close to the water, they can be completely destroyed. The image to the left shows a before and after picture of a peninsula in Malaysia.
In 2004 the tidal wave in the Indian Ocean took 230 000 lives. There were also 1 700 000 people who were forced to leave their homes and all of their belongings.
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 There is not much that can be done to stop a tidal wave, however, since the disaster of 2004 there has been a lot of research into predicting when a tidal wave will occur, and warning signals to tell people there is one coming.
Other than that, some governments have attempted to set up safety spots. This picture shows a "tidal wave tower" in Japan. |
When a tidal wave occurs the water rises much higher up the land than it normally would. This can mean that plants and animals get submerged in water.