How Do Heat and Pressure Create Metamorphic Rocks?

Objective

By applying more and more pressure to a piece of aluminum foil “clay,” we can discover, stage by stage, how heat and pressure turn clay into slate, phyllite, and finally schist.

Introduction

Slate is a metamorphic rock that’s created when clay is subjected to a lot of pressure; keep adding pressure and the slate becomes phyllite, and add a lot more pressure and heat and you get schist.

Research Questions

• Since the “ingredients” of all these different rocks are the same, what’s the difference between them?

Terms to Know

• Metamorphic rock
• Alignment of minerals

Materials

• 4 pieces of aluminum foil, about 12”x12”
• 1 hammer
• 1 surface you can pound as hard as you like
• 1 pair of safety goggles
• 1 magnifying glass
• 1 sample of dried unfired clay or mudstone
• 1 sample of slate
• 1 sample of phyllite
• 1 sample of schist.   
•                       Experimental Procedure

1. Take a piece of aluminum foil and wad it loosely into a ball. Now look at it closely. You should notice that the surface of the foil has become a lot of little flat surfaces (some will be curved, that’s okay) that are all facing different directions. Now set it down next to your sample of clay or mudstone. The molecules in it are too small to see even with the magnifying glass, but if you looked at it under a microscope you’d see that it’s made of particles that are all facing different directions, just like surfaces in the ball of foil.
2. Wad the second piece of foil into a ball like the first one and put it down on your pounding surface. Press it down really hard and squash it as flat as you can with your hand. When you look at it closely this time—you might want your magnifying glass now—you’ll see that the little surfaces are still pointing in lots of different directions, but most of them are starting to point in the same direction. This is like slate; that’s clay that has been under so much pressure that it’s turned into rock, and the particles in it are more or less lined up, or aligned, along the same plane.
3. Create a third foil ball, squash it flat with your hand, and set it on the pounding surface. Put on your safety goggles and gently whack it with the hammer until it’s about half as thick as it was before. Now it’s most like phyllite, which you should also look at with the magnifying glass. Like the minerals in the phyllite sample, most of the surfaces in the foil are pretty well aligned with each other.
4. Make one last foil ball, squash it, and whack it like you did with the last one. But this time, keep it on the pounding surface and keep your goggles on. Now you want to pound the foil as hard as you can and smash it as close to completely flat as it’ll get. Some pieces might break off; that’s okay, that happens a lot to schist when it’s forming, too. When that happens it’s called shearing. When you’ve gotten all your aggression out on that piece of foil, take a good look at it with the magnifying glass. Now you’d have a hard time finding any surfaces that aren’t facing the same direction as all the others; like the minerals in schist, which you should also look at with the magnifying glass, they’re all lined up parallel with each other.

Bibliography

• Dig It!: Over 40 Experiments in Geology, by Lockwood DeWitt and B. K. Hixson, pp. 210-217 (Loose in the Lab Science Series, 2003).

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Magnetic Linear Accelerator

Have you ever seen one of those roller coasters that shoots out of the station at an insanely high speed? These roller coasters don’t need to climb hills first to use gravitational potential energy—their power comes from magnetism and energy conservation.

A series of electromagnets (magnets made by pumping electrical current through coils of wire) alternately push and pull on the rollercoaster, pumping up its speed pretty quickly. Some engineers have imagined using the same idea to launch objects into space (from, say, a base on the Moon) without using rockets.

In this project, you’re going to build a very simple magnetic accelerator to launch steel balls at targets. What could possibly go wrong?

Problem

Build a simple magnetic linear accelerator.

Materials

• Wooden ruler with groove along the middle
• Four small, powerful magnets (e.g., neodymium magnets)
• Nine steel balls, roughly 5/8” in diameter
• Tape
• Hobby knife
• Safety Goggles

Procedure

1. Place the ruler (flat side down) on a table.

2. Lay one magnet in the ruler groove, about 2.5” from the ruler’s end. Use the tape to secure the magnet to the ruler and the knife to trim the tape to the size of the magnet.

3. Repeat step 2 with each of the remaining three magnets, placing each about 2.5” away from the preceding magnet.
4. To the right side of each magnet, place two steel balls in the groove.

5. Place a “target” a few inches to the right of the ruler. Your tape dispenser will work fine.

6. Place the ninth ball in the groove on the far left end of the ruler (opposite the target).

7. Put your safety goggles on.
8. Let the ball go and stand back!

Results

The ball will be attracted to the first magnet and set off a chain reaction of balls firing between the magnets until the last one flies off the ruler at high speed to strike its target.

Why?

What you just saw is a fantastic example of energy conservation. Energy from one ball gets transferred to the next, and then to the next, and so on. But where is all the energy in the last ball coming from if the first ball starts off from rest?

The answer is in the magnets.

Before the starting ball is released, there is potential energy stored up between the ball and the first magnet. The magnet and ball feel an attractive force, but your finger is preventing anything from happening. Once you let go of the ball, it gets drawn towards the magnet (which won’t move because it’s taped down). Potential energy gets converted to kinetic energy—the energy of motion. This is no different then holding a ball in the air and letting it go.

Eventually the ball strikes the magnet—but where does all that energy go? Well, it gets transferred to the balls on the other side of the magnet. The ball closest to the magnet is held pretty tight, but the second ball is farther away and doesn’t feel as strong an attraction to the magnet. This means there’s enough kinetic energy from the first ball to send this ball flying off with nearly the same amount of energy. (That’s why we need two balls stuck to the other side of the magnet: to lessen the attractive force a bit. Try getting it to work with only one ball loaded up next to each magnet and see what happens.)

This second ball is launched at roughly the same velocity as the first ball achieved. As this second ball gets drawn to the second magnet, the attractive force causes it to accelerate and hit the second magnet at a higher velocity than the first ball hit the first magnet. The third ball takes off with the highest velocity achieved by the second ball, and since it gets accelerated by the third magnet in turn, it strikes third magnet faster and harder than the first two balls struck their respective magnets.

Are you seeing a pattern begin to emerge? With each added magnet, more kinetic energy accumulates in each launched ball. The last ball takes off with the combined kinetic energies of all the balls that came before it!

In principle, you can add more rulers and magnets and get the final ball moving as fast as you like—up to a point. Eventually, the balls would be moving fast enough to break the magnets, a limit for which I’m sure your target is very thankful.

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ULTRASONIC OBSTACLE DETECTING ROBOT

AN ULTRASONIC OBSTACLE DETECTING ROBOT

An ultrasonic range finder is a device used to detect the range at which any obstacle is present by sending ultrasonic impulses towards the obstacle. Ultrasound is a type of transverse mechanical sound wave with frequency higher than upper audible limit of human hearing which means no human being could be able to perceive ultrasound. Their frequency limit is approximately 20 kHz to several higher GHz. These waves are generally used in RADARs and SONARs to detect incoming objects. In this robotic project, named R1, I have used an ultrasonic range finder present on a robot to detect incoming obstacles along its path. The microcontroller used in making the robot is Arduino Uno R3 processor. The different components used in it are an ultrasonic range finder HC-SR04, an Arduino Uno R3 microprocessor, a motor driver circuit and a 12V battery. The HC-SR04 has 2 ultrasonic speakers out of which one is the transmitter and the other is the receiver. The transmitter also known as the trigger pin is used to transmit ultrasound which strikes any obstacle coming in its path. After striking the obstacle the ultrasound gets reflected towards the source which is received by the receiver called the echo pin. We know that the speed of ultrasound is same as that of sound which is 330 meters per second. The purpose of HC-SR04 is to know the time delay between sending and receiving ultrasonic waves. Thus we know the time period and we know the speed, so we can be able to calculate the distance by using the formula: Distance = [(Speed x Time)/2]. We divide it by 2 since the ultrasonic wave travels the distance twice, once when transmitted and twice when received. Thus the ultrasonic range finder is used to detect the distance at which an obstacle is present. Now the controlling unit of the robot is the Arduino processor. The Arduino is so programmed that when any obstacle is present at a distance of 50 centimetres or closer the robot will take a right turn and move away else the robot moves straight forward. The power source of the robot is a 12V battery and 5V is maintained by the voltage regulator LM7805. Hence the robot works as such.

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