Monday, March 29, 2010
Sunday, March 28, 2010
Seal with Air (Page 7)
Materials:
Water
Clear glass
Cardboard card
- Fill a clear glass 3/4 full of water.
- Place cardboard card on top of glass.
- Hold on to cardboard card and flip glass over.
- Slowly remove hand from under cardboard card.
Results:
The water changed ends of the glass creating and air-tight seal holding the cardboard card to the glass preventing the water from escaping.
Science Behind Color Change
The science of color is sometimes called chromatics. It includes the perception of color by the human eye and brain, the origin in materials, color theory in art, and the physics of electromagnetic radiation in the visible range(that is, what we commonly refer to simply as light).
The color of an object depends on both the physics of the object in its environment and the characteristics of the perceiving eye and brain. Physically, objects can be said to have the color of the light leaving their surfaces, which normally depends on the spectrum of the incident illumination and the reflectance properties of the surface, as well as potentially on the angles of illumination and viewing. Some objects not only reflect light, but also transmit light or emit light themselves, which contribute to the color also. And a viewer's perception of the object's color depends not only on the spectrum of the light leaving its surface, but also on a host of contextual cues, so that the color tends to be perceived as relatively constant: that is, relatively independent of the lighting spectrum,viewing angle, etc. This effect is known as color constancy.
When a light wave with a single frequency strikes an object, a number of things could happen. The light wave could be absorbed by the object, in which case its energy is converted to heat. The light wave could be reflected by the object. And the light wave could be transmitted by the object. Rarely however does just a single frequency of light strike an object. While it does happen, it is more usual that visible light of many frequencies or even all frequencies are incident towards the surface of objects. When this occurs, objects have a tendency to selectively absorb, reflect or transmit light certain frequencies. That is, one object might reflect green light while absorbing all other frequencies of visible light. Another object might selectively transmit blue light while absorbing all other frequencies of visible light. The manner in which visible light interacts with an object is dependent upon the frequency of the light and the nature of the atoms of the object.
The color of an object depends on both the physics of the object in its environment and the characteristics of the perceiving eye and brain. Physically, objects can be said to have the color of the light leaving their surfaces, which normally depends on the spectrum of the incident illumination and the reflectance properties of the surface, as well as potentially on the angles of illumination and viewing. Some objects not only reflect light, but also transmit light or emit light themselves, which contribute to the color also. And a viewer's perception of the object's color depends not only on the spectrum of the light leaving its surface, but also on a host of contextual cues, so that the color tends to be perceived as relatively constant: that is, relatively independent of the lighting spectrum,viewing angle, etc. This effect is known as color constancy.
When a light wave with a single frequency strikes an object, a number of things could happen. The light wave could be absorbed by the object, in which case its energy is converted to heat. The light wave could be reflected by the object. And the light wave could be transmitted by the object. Rarely however does just a single frequency of light strike an object. While it does happen, it is more usual that visible light of many frequencies or even all frequencies are incident towards the surface of objects. When this occurs, objects have a tendency to selectively absorb, reflect or transmit light certain frequencies. That is, one object might reflect green light while absorbing all other frequencies of visible light. Another object might selectively transmit blue light while absorbing all other frequencies of visible light. The manner in which visible light interacts with an object is dependent upon the frequency of the light and the nature of the atoms of the object.
Change Color (Page 53)
Materials:
Red and Green cellophane
Flashlight
Black box with hole in one side
Red playing card
Banana
Green apple
1. Place the objects in the box. Place the green
cellophane over the top of the box and shine
a flashlight through the hole in the side.
* The banana and the apple both reflect
green light.
* The red playing card doesn't reflect
green light, so the red on the card
appears black.
2. Do the same thing, but use
the red cellophane.
* The banana reflects the red light,but the apple doesn't.
* The card reflects all colors, so now it looks red.
(Sam and I tried this with another color of red and it didn't work, but she found this one and it worked perfectly).
Red and Green cellophane
Flashlight
Black box with hole in one side
Red playing card
Banana
Green apple
1. Place the objects in the box. Place the green
cellophane over the top of the box and shine
a flashlight through the hole in the side.
* The banana and the apple both reflect
green light.
* The red playing card doesn't reflect
green light, so the red on the card
appears black.
2. Do the same thing, but use
the red cellophane.* The banana reflects the red light,but the apple doesn't.
* The card reflects all colors, so now it looks red.
(Sam and I tried this with another color of red and it didn't work, but she found this one and it worked perfectly).
Build a Water Wheel (Page 116-117)
Materials: Cork
Funnel with plastic tube
Scissors
Modeling clay
Stiff plastic
Two toothpicks
Pitcher with water
Glass dish
2 liter plastic bottle
Nail
Knife
Tape
Step 1: Using the knife, cut 4, evenly spaced, slits into the cork.
Step 2: Cut out 4 pieces of stiff plastic, making them the same size and length as the cork.
Step 3: Fit the pieces of plastic into the slits, making sure they fit tight.
This is the water wheel
Step 4: Using the nail, pierce 2 holes in opposite sides of the bottle.
Step 5: Cut off the bottom of the bottle. Make sure the edge is straight so the bottle can stand upright.
Step 6: Push a toothpick into one end of the cork, then fit it into one hole in the bottle.
Step 7: Push the other toothpick through the other hole and into the cork.
Step 8: Put modeling clay onto both ends of the toothpicks so the water wheel can spin easily.
Step 9: Place the bottle in the dish and place the tube into the neck of the bottle. 
Step 10: Pour the water into the funnel and the waterwheel will spin. (The closer the tube is to the water wheel, the faster it will spin.)History of the Waterwheel
A water-wheel is a hydropower system, a system for extracting power from a flow of water. It was a widely used system in the middle ages, powering most industry in Europe, along with the windmill. The most common use of the waterwheel was to mill flour, where it was known as the watermill, but other uses included machining and pounding linen for use in paper.
A water-wheel consists of a large wheel, typically wooden, with a number of blades or buckets arranged on the outside rim forming the driving surface. The wheel is mounted vertically on a horizontal axle that is used as a power take-off. Water-wheels come in two basic forms – under-shot and over-shot.
The over-shot wheel has the water channeled to the wheel at the top and slightly to one side in the direction of rotation. The water collects in the buckets on that side of the wheel, making it heavier than the other "empty" side. The weight turns the wheel, and the water flows out into the tail-water when the wheel rotates enough to invert the buckets. The over-shot design uses almost all of the water flow for power (unless there is a leak) and does not require rapid flow.
The under-shot design places the wheel over a fast-flowing body of water. Here is the flow of the water directly against the buckets (or paddles) that turns the wheel, not the weight. It has the advantage of being more powerful, but can only be used where the flow rate is sufficient to provide torque.
A more modern design of the under-shot system combines the features of the over-shot as well. In this version the water stream is "dug out" below the wheel, so the water has to flow against the buckets, as well as fill them and drain out as in the over-shot design. This version captures power from both the flow and the weight, and became the most popular version throughout Europe.
A water-wheel consists of a large wheel, typically wooden, with a number of blades or buckets arranged on the outside rim forming the driving surface. The wheel is mounted vertically on a horizontal axle that is used as a power take-off. Water-wheels come in two basic forms – under-shot and over-shot.
The over-shot wheel has the water channeled to the wheel at the top and slightly to one side in the direction of rotation. The water collects in the buckets on that side of the wheel, making it heavier than the other "empty" side. The weight turns the wheel, and the water flows out into the tail-water when the wheel rotates enough to invert the buckets. The over-shot design uses almost all of the water flow for power (unless there is a leak) and does not require rapid flow.
The under-shot design places the wheel over a fast-flowing body of water. Here is the flow of the water directly against the buckets (or paddles) that turns the wheel, not the weight. It has the advantage of being more powerful, but can only be used where the flow rate is sufficient to provide torque.
A more modern design of the under-shot system combines the features of the over-shot as well. In this version the water stream is "dug out" below the wheel, so the water has to flow against the buckets, as well as fill them and drain out as in the over-shot design. This version captures power from both the flow and the weight, and became the most popular version throughout Europe.
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