Archimedes Screw

Can you find out how many screws there are in the water area? How do they compare in size? Why do you think this is important? How many times do you have to turn the screw to get the water to fill up the bucket? Is the number always the same? Is this an efficient way to move water up a hill? If you stop turning the screw what happens to the water? Visitors can see how the screw traps water in the lower part at each turn, and then moves that water higher and higher as you turn the whole contraption? The water has traveled a greater distance than if you lifted a bucket vertically up to the top. The greater distance traveled by the turning of the screw, plus the leverage of the wheel and axle mechanism, make the water easier to move. The design of the Archimedes Screw is a wheel and axle—a simple machine that transforms a small turning force at the outside of the wheel into a large turning force closer to the axle. A wheel and axle is like a rotating lever. The size of the wheel determines the distance from the axle (fulcrum). You can trade off distance for force. The larger the wheel, or distance from the axle, the less force required to turn it but the farther you must move.

Ball Run

Here, visitors pick one of the different colored balls and follow it along its journey. They can describe its path and question: How many times does it fall, climb and spin? How did it get up to its highest point? A ball in your hand has the potential to do a lot of things. If dropped from a height, it can fall fast, break something, or bounce. Releasing the ball changes its potential energy into kinetic (moving) energy. In the ball run, each ball is given potential energy from the mechanical energy of the conveyor belt lifting it to its greatest height. As the ball moves along the track, it gains kinetic energy. As the ball changes direction, it also changes energy.

Big Ears

At this exhibit, visitors listen to the sound of the Science Playground by using Big Ears. They place their ears between the rubber guards and listen if they hear low-pitched sounds or high-pitched sounds. Sound travels in all directions as vibrations. Sound waves hitting the parabolic dishes (the Big Ear dishes) from the direction that they are facing causes them to vibrate. Sound that would normally be lost in passing over an open tube, such as a Palm Pipe, is caught by the Big Ears dishes to increase the amount of sound that can be heard. The vibrating dish sets the tube to vibrate, which in turn sets the air in the tube to vibrate. The vibration of the air travels down the ear guards where it is heard as sound. The long pipe reinforces low-pitched, low-frequency sounds in the same way as the long pipes of the Palm Pipes.

Energy Wave

Visitors turn a large wheel and send a wave down a 150-foot length of connected rods and balls. What happens afterward? Investigations can occur on the distance that each ball moves up and down or the frequency of how fast the wheel is turned left to right. The action of turning the wheel sends a wave down the long series of connected rods and balls. When the wave reaches the end, it is reflected back to the visitor, encountering further waves that they may be sending. When a traveling wave encounters a reflected wave, they fall on top of each other, either adding or subtracting their motions, depending on exactly when they meet. Where the two waves add together, the rods move up and down more strongly. Where they subtract, there is no motion. This gives the appearance of the wave standing in place, moving only up and down.

Giant Lever

At this exhibit, visitors try to move a 700-pound-barrel by pulling each of the ropes. How hard is it to move the barrel with each rope? Can they figure out which rope will make moving the barrel easier? How does pulling down on each rope feel? Which rope is better to use to move the barrel? Why? What do the numbers written above each rope mean? "Give me a place to stand and I will move the Earth," said Archimedes, an ancient Greek philosopher. A simple machine such as a lever can make easy work of moving heavy objects. Levers let you reduce your effort while increasing outcome. A lever requires a fulcrum (a point of balance) in order to do work. How much effort it takes to lift the weight depends on your distance from the fulcrum. In this exhibit, the barrel is near the fulcrum. When you pull the rope closest to the fulcrum, a large force is required, although you only need to move the rope a short distance. When you pull the rope farthest away from the fulcrum, less force is required, but you need to pull a longer distance. Levers let you make a trade-off between the amount of force you need to apply and the distance you move the lever.

Giant Seesaw

The weight of the Giant Seesaw's platform is perfectly balanced on its central pivot, or fulcrum. Visitors can walk across the platform from end to end. How does their weight at either end effect its balance? Along with some friends, visitors can try to find a new balance. How can they upset that balance? They can have their friends stand on one side of the central pivot or fulcrum. How can they position themselves to be able to lift your friends? One person can make a difference! The Seesaw is a simple machine called a lever. Simple machines make doing work easier. If you're farther from the fulcrum, your body has a bigger impact on the seesaw. A small force (your weight) far from the fulcrum can balance a much larger force (the weight of your friends) if it is nearer to the fulcrum. In other words, a small force yours over a large distance is equal to a large force over a small distance.

Octascope

Here, visitors look through the eyepiece at something on the Science Playground. They explore how the image looks as it is multiplied in the kaleidoscope. A kaleidoscope is a tube containing mirrors that reflect multiple images. Here it multiplies the image eight times. The disc contains bits of colored plastic and adds even more patterns to the multiple images of the Science Playground. Kaleidoscope comes from the Greek words "Kalo" (beautiful), "eido" (shape), and "scope" (to view).

Periscope

Looking through the periscope, visitors can explore how images are manipulated. The periscope is a tubular optical instrument containing lenses and mirrors that can help you see over walls, around corners or other obstacles. The simplest type of periscope consists of a tube with one mirror at each end, parallel to each other but at 45 degrees to the axis of the tube. This device produces no magnification. The first mirror deflects the light down through the vertical tube, the second diverts it horizontally so that the scene can be viewed conveniently through the viewfinder. The longer or narrower the tube, the smaller the field of view you get. More complicated periscopes, like this one, have a system of lenses inside the tube which gives you a greater field of view than it would be if the tube had only mirrors at the top and bottom. Inside this tube, a series of "relay lenses" serve to reproduce the image coming in the top of the tube every few feet, all the way down to your eye. This way, you have just as wide a field of view as you would have if the tube were only four feet long, instead of the actual 16 feet. This periscope also has magnifying lenses, enlarging what you see about two times. Periscopes have been widely used in submarines, tanks and other armored vehicles as observation devices for the driver, gunner and commander. The modern equivalent of these periscopes, often made with fiber optics and video cameras, are used to see inside complex machinery, to study fish underwater, and to make medical examinations deep inside the human body.

Propeller/Water Wheel

Visitors can fill the table with water using the stainless steel bucket and turn either the crank for the propeller or the one for the water wheel. Which moves more water? What happens to the water wheel when you turn the propeller? How can you make the water in the table flow in different directions? What happens when you add more water? As you turn the crank you give energy to the water, causing it to flow. The moving water pushes on the paddles of the water wheel, causing it to turn. The opposite also happens when you turn the water wheel, water flows to the propeller and causes it to turn. The water wheel spins around an axle. If this axle were attached to other machines, it would be able to run them using the energy of the water.

Slides

The two slides offer two different ways of doing the same thing. Even though they are not the same shape, they are both ramps. One is mostly straight while the other is longer and curved more steeply. Which will get you down more quickly? Why? What factors may determine how fast you come down the slides? Slides are examples of ramps or inclined planes that let you go down easier. And they're fun! The shape of the slide makes a difference. In both cases, gravity accelerates you down. The steeper start with the curved slide lets gravity speed you up right away, and the extra speed stays with you through the rest of your journey down. With the straight slide, gravity works uniformly throughout your trip, so you don't get the benefit of the quick shot of energy in the first few feet. By the end, your total energy is the same either way, but the trip was quicker on the curved slide because you generated more of the kinetic energy at the beginning.

Sound Steps

Here visitors step on the three wooden beams one at a time. The seesaw movement of the wooden beams operates a bellows, a device that forces air through the musical pipes creating six different notes or sounds. This type of airflow is used in wind organs and harmonicas. Each note or sound is a different wavelength. Just as different wavelengths of light are perceived as different colors, different wavelengths of sound are perceived as different notes.

Speaking Tube

Visitors can talk into one end, and have someone listen on the other end. Can they hear each other? How does one person's voice get through hundreds of feet of tubing encircling the playground structure? Does the other person hear you exactly at the same time the first person speaks into the tube? Sound is a vibration that travels through the air as a wave. Once any wave is started it keeps going, just like the Energy Wave exhibit, until it is absorbed by something. Energy can also fade away as it spreads out in all directions. In the speaking tube, the sound waves created by your voice have nowhere to go except through the tube. The rigid tube does not absorb much sound so very little energy is lost as sound travels through the tube. But there is a short delay from the moment you speak to the moment you are heard because the energy must travel quite a distance through the tube.

Standing Spinner

At this exhibit, visitors stand up straight on the spinner, hold on firmly, and push off with one foot to spin. While holding onto the pedestal, they can lean their body out. As they keep spinning, they then pull in and stand up straight. What happens this time? Whenever anything spins around an axis (a central point) bringing it closer to that axis will cause it to spin faster. Figure skaters spin faster when their arms are closer to their bodies than when they spread their arms out. They slow the speed of their spin by stretching out their arms. In both cases, the figure skater's momentum stays the same (a physicist would say that angular momentum is conserved). The spinning gradually slows and comes to a stop because the energy is slowly transformed into heat through friction. Atoms, planets and galaxies conserve angular momentum, too.

Stream Table

Visitors can set up barriers along the length of the table, creating a series of dams and locks. Using the Archimedes screw to fill the table with water, they can notice interesting things about the speed of the water flowing through the openings or locks and the height of the water being blocked by the dams. You can see how currents of water vary their speed, depth and direction of flow as they encounter various dams and locks. As the water falls onto the table, its moving (kinetic) energy increases. Dams block the flow of water and both decrease the water's flow and increase its height. The dams and locks cause the water to rise and slow down. When the water level rises, its kinetic energy decreases (it moves more slowly) while its potential energy increases. When the water level falls, its kinetic energy increases (it moves faster) and its potential energy decreases.

Sun Catchers and the Kinetic Sculpture

Visitors can grasp and rotate the mirrors using the handles. They can experiment by directing a sunbeam using the mirror to one of the targets on the sculpture. Some of the sun's energy reflected from the flat mirror can be directed at the bull's-eye targets. Within each bull's eye, there is a light activated switch. When light hits it, the switch allows an electric current to flow, activating a motor. The motor turns the propellers and activates the fog machine.

3-D Spider Web

Would a spider at the top of the web know you were climbing at the bottom? How? Visitors climb up one end of the web while a friend can climb up the opposite end. Can you see or feel the vibration of the web? Can you find places where you do not feel a vibration? Whenever you push or pull an object, that object pushes or pulls back. The action of climbing is met by an equal but opposite reaction by the entire web, because each of the hexagon-shaped loops is connected. In monkey bars, a relatively rigid structure, you do not notice this reaction. You can see and feel the range of movement better in the loops of the 3-D Spider Web.

Vertical Energy Wave

Visitors pull on a cord to send a wave down a length of connected rods and balls. What happens afterward? Investigations can occur on the distance that each ball moves up and down or the frequency of how fast the cord is pulled. When the wave reaches the end, it is reflected back to the visitor, encountering further waves that they may be sending. When a traveling wave encounters a reflected wave, they fall on top of each other, either adding or subtracting their motions, depending on exactly when they meet. Where the two waves add together, the rods move up and down more strongly. Where they subtract, there is no motion. This gives the appearance of the wave standing in place, moving only up and down.

Wave Machine

Using the stainless steel bucket, visitors fill the wave machine with water and move the paddle back and forth. They can also arrange the barriers so that the water has to pass between them. Waves of water travel as peaks and valleys. As a wave approaches a barrier it must go around, the wave splits. The two or more parts of the wave then interact with each other as they collide on the other side of the barrier, forming a new pattern. Have you ever dropped a pebble into a pond and noticed the ripples? Have you ever tried dropping two pebbles and watched how the ripples interact? When ripples collide, they either work together or against each other. This new pattern is a combination of two or more waves.

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