Posted by David Wetzel
Math Problem of the Week
Three people walk into a motel and ask for a room. The desk clerk says a room costs 60 dollars, so each person pays 20 dollars towards the cost.
Later, the clerk realizes he made a mistake, that the room should have only been 55 dollars.
He calls the bellboy over and asks him to refund the other 5 dollars to the 3 people.
The bellboy, not wanting to make a mess dividing the 5 dollars three ways, decides to lie about the price, refunding each person 1 dollar, keeping the other 2 dollars for himself.
Ultimately each person paid 19 dollars towards the room and the bellboy got 2 dollars, for a total of 59 dollars.
But the original charge was 60 dollars. Where did the other dollar go?
Resources
12 Tips for Solving Word Problems
Math Problem Solving
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Filed Under: Math
Posted by David Wetzel
Plants
Plants are the most versatile organic material on earth. Without plants life on earth would have evolved in a whole new direction or not at all. When you look out the window, stand in your year, or talk a walk in a forest just think about the versatility of all the plants you see around you.
The Versatility of Plants
These are some of the uses of plants today:
- Plants provide us with food to eat - vegetables and fruits. Plants also provide food for most animals and many fish that we eat. So with out plants we would not have vegetables, fruits, meats, and fish to eat.
- Plants make the oxygen that humans, animals, and some fish breathe. Through the process of photosynthesis, where carbon dioxide is converted into oxygen, we would not survive. Makes you wonder what will happen to mankind when all the trees are cut down and the carbon dioxide in the earth’s atmosphere can no longer be converted to oxygen. Global warming anyone?
- Plants provide habitats for animals. These plants provide food, shelter, and safety for these animals. As global warming continues to increase the minor affects are are animals begin to lose their habitat. A major affect is that rain fall patterns are affected all around the earth as tropical rain forests disappear.
- Plants decompose as they die and fertilize the soil to keep the soil rich in nutrients. Without plants the soil will be eroded away by weathering creating loss of habitat for animals and the ability to grow food for humans.
- Plants filter out some of the harmful materials that enter the ground, water, and air. For example the household corn plant is known for its ability to filter toxins from the air we breathe. Wetlands provide a habitat for animals, fish, and birds; they also filter some pollutants that enter the water.
- Plants provide many of the materials we use today such as wood for shelter, furniture, and medicines. Many of the fuels we use today are derived from plants that covered the earth millions of years ago such as coal and oil.
- Plants provide the beauty of the scenery in which we began this journey. Trees, shrubs, and flowers make the view of the outside world much nicer.
The Life Cycle of Plants
Life Cycle of Plants
Why We Need Plants
We need plants to survive, because they provide people with food and convert CO2 into Oxygen.
Additional Resources
Greenhouse Effect
Life Cycle of Plants
Posted by David Wetzel
Twinkling Stars
Stars twinkle because of turbulence in the Earth’s atmosphere. Light from distant stars passes through various layers in the Earth’s atmosphere, and it gets refracted depending on the temperature and density of the air at that point.
So light will pass through one layer, be refracted at one angle, and then pass through a different layer and be refracted at a different angle.
When you see a twinkling star, you’re seeing the accumulated refractions from all those layers, which change the position and size of the star - many times a second.
Because of this “chromatic aberration,” stars can appear to change colors when they are twinkling strongly.
On a clear, dark night, our eyes can see about 6,000 or so stars in the sky. They seem to twinkle, or change their brightness, all the time. In fact, most of the stars are shining with a steady light. This means that some of the light reaches us directly and some gets bent slightly away. To our eyes, this makes the star seem to twinkle.
You will notice that stars closer to the horizon appear to twinkle more than other stars. This is because there is a lot more atmosphere between you and a star near the horizon than between you and a star higher in the sky. Go out some night soon and have a look!
In outer space, where there is no atmosphere, stars do not twinkle. This is why the Hubble Space Telescope can produce the brilliant and crisp images of the universe that we have come to know. At our Earthbound observatories, we are learning how to compensate for the twinkling effect by adapting the optics of our large telescopes as fast as it occurs. As a result, we should soon be able to produce much sharper images from here on the ground.
For example, the Pleiades Star Cluster taken from the Hubble Space Telescope:
Notice that the stars are clear, bright and are not twinkling.
Resources
Atmospheric Distortion
Hubble Telescope
Google Earth’s Sky
