Build a Gauss Rifle! Abstract. Objective. Introduction. Difficulty. Prerequisites

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1 Build a Gauss Rifle! Difficulty Time Required Prerequisites Material Availability Average (about one week) None In order to do this science project, you will need neodymium magnets and steel ball bearings. See the Materials and Equipment list for details. You will also need a calculator or computer with the square root function. Cost Average ($0 - $00) Safety A Gauss rifle can produce high velocity projectiles. Do not aim the gun at anyone or anything; do not put your hand in front of the projectile. Operate the Gauss rifle safely. Be sure to read the important safety notes at the beginning of the Experimental Procedure before you begin. Scissors or other metal objects may be attracted to the magnets; use caution when using metal objects near the magnets. Abstract What can you do with magnets and ball bearings that makes a lot of noise? Why, build a magnetic rifle, called a Gauss rifle, of course! Now, this rifle is not a weapon, but a way for you to learn a lot more about physics concepts, like momentum. In this physics science project, you will investigate how far a ball bearing launched by a Gauss rifle will fly, depending on how many magnetic acceleration stages are in the rifle and the ball bearing's initial velocity. This science project makes for a really cool visual demonstration. Objective In this science project, you will build a Gauss rifle and determine the effect the number of magnet stages has on the flight distance and velocity of ball bearings. Introduction Have you ever played with magnets, sticking them together and pulling them apart? Maybe you have seen how magnets attract paper clips and pins? Have you ever felt that tug when you tried to remove something from the magnet? If you have, then you have experienced the effects of magnetic fields. A magnetic field is a force that comes from a magnet, and it is either attractive (meaning it attracts) or repulsive (meaning it repels). A magnetic field is a force, just like gravity, and it can have magnitude and direction. You might be thinking, "Great, magnets have magnetic fields, so what? What kinds of things can I do with magnets, other than just sticking them to stuff?" Well, it turns out that magnetic fields are used in all kinds of things, like circuits, motors, compasses, and MRI equipment. In this physics science project, you will see a magnetic field at work and use it to make a neat toy called a Gauss rifle. This rifle is named after Carl Gauss, who discovered the equations that

2 describe magnetic accelerators, including the Gauss rifle. Don't worry; this rifle is not used to shoot things but to demonstrate physics principles like magnetism, and others that are discussed below. A Gauss rifle is made up of at least one magnet stage, but it could have several successive magnet stages. A magnet stage is a magnet with several ball bearings touching it on one side. The first magnet stage in this science project will have another ball bearing on its other side, which we will call the "trigger" ball. To get the Gauss rifle to shoot a ball bearing, the trigger ball rolls toward the first magnet stage and then hits the first magnet. This starts a chain reaction that ends with the last ball bearing being ejected from the gun. Watch the video below to see a Gauss rifle in action. Watch this video and see a cool demonstration of a one-magnet stage Gauss rifle. So how does a Gauss rifle work? When you give the trigger ball a slight nudge, it moves forward. As it gets closer to the neodymium magnet, the magnetic field pulls the ball toward the magnet. The ball bearing accelerates toward the magnet due to the magnetic field. When the trigger ball bearing hits the magnet, it transfers its energy and momentum to the magnet. Without moving, the magnet then transfers the momentum from the trigger ball to the first ball bearing on opposite side of the magnet. This concept is called conservation of momentum. The ball bearing then hits the ball bearing next to it and momentum keeps getting transferred until the last ball bearing shoots off. In a rifle with more than one magnet stage, the magnetic field from the second magnet attracts this last ball bearing, the ball bearing accelerates toward the second magnet, and the process starts again. The only difference is that the ball bearing from the previous magnet stage gives the second magnet more energy than the ball bearing that started the chain reaction. So how fast is the final ball bearing going when it leaves the rifle? What is its velocity? How far will it go? In this physics science project, you will answer these questions and look at how the velocity of the final ball bearing depends on the number of magnet stages. The distance that the ball travels will depend on how fast the ball was going when it was shot, as well as on gravity the force that attracts everything on Earth which will eventually pull the ball down. The Gauss rifle is not only a great toy for demonstration, but also a cool way to gain a whole lot of physics knowledge.

3 Terms and Concepts Questions Magnetic field Force Magnitude Acceleration Energy Momentum Conservation of momentum Velocity Gravity Data Square root Trajectory What is a magnet and what are some magnetic materials? What is the difference between velocity and acceleration? What is conservation of momentum and what are Newton's laws of motion? Bibliography These sources go into more detail about the physics of horizontally launched projectiles, the kind of physics that will help you understand how far a ball bearing launched by the Gauss rifle will travel. The Physics Classroom. (00). Horizontally Launched Projectile. Retrieved October 7, 00, from ( sicsclassroom.com/mmedia/v ectors/hlp.cf m) Wikipedia Contributors. (00, August 7). Trajectory of a Projectile. Wik ipedia: The Online Encyclopedia. Retrieved October 7, 00, from title=trajectory_of_a_projectile&oldid=89 ( _of _a_projectile&oldid=89) HyperPhysics. (n.d.). Trajectories. Retrieved October 7, 00, from ( perphy sics.phy -astr.gsu.edu/hbase/traj.html) Materials and Equipment Wooden dowels, 6 inches long and ⅜ inch diameter () Neodymium magnets, ¼ inch thick and ½ inch diameter (8) Nickel-plated steel balls, ½ inch in diameter (0) Elmer's Carpenter's Wood Glue Clear tape, ½ inch in diameter Plastic box, approximately the size of a shoe box Sand, cups Tape measure (metric) Table in front of which there is ample room and will not be a lot of foot traffic Calculator with square root function Science Buddies Kit: This item is not included because you can calculate square roots using a free online calculator like ecalc.com ( not including the calculator helps make the kit more affordable. Lab notebook

4 Shop for Supplies at Science Buddies Online Store ( Science Buddies has compiled some suggestions for harder to find items in our Amazon store. The store does not include every item for every project, but it does include items that we feel work for the projects on our website. If you have comments or would like us to add items to the store, please contact us at Experimental Procedure Safety Notes about Neodymium Magnets: (Those in quotes are from K&J Magnetics, 006) "The neodymium magnets [used in this project] are extremely strong, and must be handled with care to avoid personal injury and damage to the magnets. Fingers and other body parts can get severely pinched between two attracting magnets. Neodymium magnets are brittle, and can peel, crack or shatter if allowed to slam together. Eye protection should be worn when handling these magnets, because shattering magnets can launch pieces at great speeds." "The strong magnetic fields of neodymium magnets can also damage magnetic media such as floppy disks, credit cards, magnetic I.D. cards, cassette tapes, video tapes or other such devices. They can also damage televisions, VCRs, computer monitors and other CRT displays. Never place neodymium magnets near electronic appliances." "Children should not be allowed to handle neodymium magnets as they can be dangerous. Small magnets pose a choking hazard and should never be swallowed or inserted into any part of the body." "Never allow neodymium magnets near a person with a pacemaker or similar medical aid. The strong magnetic fields of the magnet can affect the operation of such devices." "Neodymium magnets are brittle and prone to chipping and cracking. They do not take kindly to machining." "Neodymium magnets will lose their magnetic properties if heated above 7 F (80 C)." "Neodymium magnets should never be burned, as burning them will create toxic fumes." "Like any tool or toy, neodymium magnets can be fun and useful, but must always be treated with care." If you need to separate the magnets, they can usually be separated by hand one at a time by sliding the end magnet off the stack. If you cannot separate them this way, try using the edge of a table or a countertop. Place the magnets on a tabletop with one of the magnets hanging over the edge. Then, using your body weight, hold the stack of magnets on the table and push down with the palm of your hand on the magnet hanging over the edge. With a little work and practice, you should be able to slide the magnets apart. Just be careful that they do not snap back together once you have separated them. Building the Slide for the Rifle. You are going to use the two wooden dowels to make a slide on which the magnets and balls will sit on and move down.. Place the dowels evenly next to each other and make sure the ends are flush (lined up). Use clear tape to tape the dowels together at both ends. The tape will temporarily hold them together.. Place the taped dowels on the table and then carefully glue them together with wood glue. Try to prevent the glue from leaking through to the other side. a. Science Buddies Kit: The kit includes cotton swabs, which are helpful for applying the wood glue.. Let the glue dry (this may take a few hours, depending on the humidity) and then take the pieces of tape off.

5 Setting Up the Experiment. Place the wood slide on the table with the glued side down. Put two ¼ inch thick magnets together to form a ½ inch thick pair of magnets. Use this pair of magnets as a unit in your Gauss rifle. Put the neodymium magnet pair on the slide, toward one end. Place two ball bearings on one side of the magnets such that the last ball is at the end of slide. See Figure. This step is represented by the magnet and ball bearings on right edge of the table in the figure. a. Science Buddies Kit: If your magnets came with foam spacers between them, remove the foam spacers before using the magnets. Figure. A one-magnet stage Gauss rifle.. Now wrap a piece of tape around the magnet so that the ends of the tape wrap around the wood slide. Remove the ball bearings. a. Troubleshooting Tip: If you have problems with the magnet pulling out from the tape or with the tape breaking, then add a second layer of tape for reinforcement.. Place the wood slide on the table so that the end of the slide is flush with the end of the table. See Figure.. Place two ball bearings on one side of the magnet, at the end of the slide (where they were located in step ).. Pour the sand in the plastic box and smooth it out so that the sand is approximately level. Place the box on the floor a couple of feet away from the edge of the table. 6. Place one ball bearing on the other side of the magnet, about centimeters (cm) from the magnet. This is the trigger ball. See Figure. Figure. A one-stage Gauss rifle. Note the two ball bearings touching the magnet stage at the end of the slide (as described in step ) and the single ball bearing (the trigger ball) cm behind the magnet stage (as described in step 6).

6 7. Measure the height of the table, in meters (m), on which the Gauss rifle is sitting. Record this value in your lab notebook. Shooting the One Magnet Stage Gauss Rifle. Practice shooting the Gauss rifle so that you can place the plastic box at the correct distance for accurate measurements, as follows. Your experiment will look something like Figure. a. Lift the slide just a little to get the trigger ball rolling toward the magnet. Keep an eye on the last ball and watch where it lands so that you know where to place the plastic box. Caution: Be sure there is nothing breakable and nobody in front of the setup before you begin testing. b. Place the box so that the ball will land approximately in the middle of the plastic box.. Now make a data table, like the one below, in your lab notebook so you can record the data that you get from your experiments. Height of table (m)= Number of Magnet Stages Trial Distance the Ball Traveled (m)

7 . Replace the correct number of balls on either side of the magnet. a. Troubleshooting Tip: You may find it helpful to stabilize the magnet with one hand while repositioning the ball bearings. This keeps the tape holding the magnet to the wooden dowels from stretching or breaking as you reset the rifle. It is often easier to reset the rifle by sliding the ball bearings around the magnets instead of trying to pull them off the magnets.. Now lift the slide just a little to get the trigger ball rolling toward the magnet. After the launched ball lands, take the tape measure and measure the horizontal distance from the edge of the table to the spot where the ball first landed in the box. Record this distance in meters (m) in the data table in your lab notebook. a. Troubleshooting Tip: Sometimes the ball bearing will roll or bounce after it first hits the sand. You want to measure the distance from the edge of the table to where the ball first hit the sand, not the distance from the edge of the table to where the ball finally comes to rest. See Figure. Figure. In this case, the launched ball bearing landed in the crater at left, then bounced and slid to where it finally stopped at the right side of the box. The tape measure is positioned to start measuring from the circular crater at left the place where the ball bearing first hit the sand.. Retrieve the ball from the box, smooth the sand, and replace the ball in its original position on the slide. 6. Repeat steps - four more times for a total of five trials. It is a good idea to repeat your experiments to make sure that your data is reproducible and accurate. Shooting a Multiple Stage Gauss Rifle. You now have data for a one-magnet stage Gauss rifle. But what happens when you have more than one magnet stage?. Build a two-magnet stage Gauss rifle. Remove the ball bearings from the rifle. Place the second magnet stage 0 cm to the left of the first magnet stage (as measured from the front of the first magnet stage to the front of the second magnet stage) and tape it to the wood slide. Cut off any excess tape, if needed. See Figure. a. Troubleshooting Tip: Depending on the strength of your magnets, 0 cm between stages may not be enough space. If you have problems with the magnet stages pulling together (instead of staying separated) due to their magnetic attraction, simply increase the spacing between magnet stages. If you do change

8 the spacing, be sure to use the same spacing between all of the magnet stages in your Gauss rifle. Figure. The magnet stages are spaced 0 cm apart, as measured from the front of the first magnet stage (at right) and the front of the second magnet stage (at left).. Now place two ball bearings on one side of each magnet stage. Place the trigger ball cm to the left of the second magnet. Figure shows how to arrange the magnets and ball bearings. Figure. A four-stage Gauss rifle with the "trigger" ball bearing cm to the left of the fourth stage. A two-stage rifle has two magnet stages, with the "trigger" ball bearing cm from the second stage. Similarly, a three-stage rifle has three magnet stages, with the "trigger" ball bearing cm from the third stage. In each case, the magnet stages are 0 cm apart from one another.. Practice shooting the Gauss rifle so that you can place the plastic box at the correct distance for accurate measurements. a. Lift the slide just a little to get the trigger ball rolling toward the magnet. Keep an eye on the launched ball and watch where it lands so you know where to place the plastic box. b. Place the box so that the launched ball will land approximately in the middle of the box.. Retrieve the ball from the box, smooth the sand, reset the rifle, and replace the launched ball in its original position on the slide. 6. Lift the slide a tiny amount to get the trigger ball rolling toward the magnet. After the launched ball lands, take the tape measure and measure the horizontal distance from the edge of the table to the spot where the ball first landed in the box. Record this distance in meters (m) in the data table in your lab notebook. 7. Repeat steps -6 four more times for a total of five trials. It is important to repeat your experiments to make sure that your data is reproducible and accurate. 8. Repeat steps -7 for a three-magnet stage Gauss rifle. Remember to record all data in your data table in your lab notebook. 9. Repeat steps -7 for a four-magnet stage Gauss rifle. Remember to record all data in your data table in your lab notebook. Analyzing the Data. Now review the data you collected in the previous two sections.. Create a plot showing the relationship between distance traveled and the number of magnet stages.. Now use Equation to calculate the velocity at which the ball was launched from the wood slide (the Gauss rifle). Record your results in a table, like the one shown below.

9 a. Troubleshooting Tip: Make sure that you use consistent units in your calculations. If you measured the table height and distance traveled in units other than meters, you will need to convert those measurements to meters. Equation : Velocity (m/second) = Horizontal distance between the table and the ball (m) X Square root of (gravitational acceleration (m/second) divided by [ X height of the table (m)]) V = D( g ) h V = Velocity of ball ejected from rifle, in meters/second (m/s) D = Horizontal distance between the edge of the table and where the ball landed, in meters (m) g = Gravitational acceleration which is 9.8 meters/(second squared) h = Height of table, in meters (m). Number of Magnet Stages Trial Distance the Ball Traveled (m) Velocity of the Ejected Ball (m/s)

10 . Average the data from the table above. Average the velocity for each magnet stage (,,, or ) over the five trials. Record your data in a table like the one shown below. Number of Magnet Stages Average Velocity of the Ejected Ball (m/s). Now make a plot of the average velocity dependent upon the number of magnet stages. Label the x-axis Magnet Stages and the y-axis Average Velocity. 6. What do the plots that you made tell you? How is velocity affected by the increase in magnet stages? Troubleshooting For troubleshooting tips, please read our FAQ for Build a Gauss Rifle Project ( airprojects/phpbb/v iewtopic.php?f =67&t=96). Variations Buy additional components and incrementally increase the number of magnet stages until you get to eight magnet stages. Does the velocity increase or decrease with the increase in magnet stages? Try increasing the distance between magnet stages. How does this affect velocity? Science Buddies Kit: What happens if you use only one ¼" thick magnet in each magnet stage, instead of two? Equation does not account for the effect of air resistance. How do you think air resistance affects the distance and trajectory that the ball bearing will travel? Check out the references listed in the Bibliography for more information on how to derive equation. Related Links Science Fair Project Guide ( air-projects/project_guide_index.shtml) Other Ideas Like This ( air-projects/recommender_results.php?solt=phy s_p08.shtml) Physics Project Ideas ( air-projects/recommender_interest_area.php?ia=phy s) My Favorites ( air-projects/recommender_show_f av orites.php) FAQ for Build a Gauss Rifle Project ( air-projects/phpbb/v iewtopic.php?f =67&t=96) If you like this project, you might enjoy exploring this related careers: Physicist

11 Physicists have a big goal in mind to understand the nature of the entire universe and everything in it! To reach that goal, they observe and measure natural events seen on Earth and in the universe, and then develop theories, using mathematics, to explain why those phenomena occur. Physicists take on the challenge of explaining events that happen on the grandest scale imaginable to those that happen at the level of the smallest atomic particles. Their theories are then applied to human-scale projects to bring people new technologies, like computers, lasers, and fusion energy. Read more ( air-projects/science-engineering-careers/phy s_phy sicist_c00.shtml) Materials Scientist and Engineer What makes it possible to create high-technology objects like computers and sports gear? It's the materials inside those products. Materials scientists and engineers develop materials, like metals, ceramics, polymers, and composites, that other engineers need for their designs. Materials scientists and engineers think atomically (meaning they understand things at the nanoscale level), but they design microscopically (at the level of a microscope), and their materials are used macroscopically (at the level the eye can see). From heat shields in space, prosthetic limbs, semiconductors, and sunscreens to snowboards, race cars, hard drives, and baking dishes, materials scientists and engineers make the materials that make life better. Read more ( air-projects/science-engineering-careers/matlsci_materialsscientistsandengineers_c00.shtml) Aerospace Engineer Humans have always longed to fly and to make other things fly, both through the air and into outer space aerospace engineers are the people that make those dreams come true. They design, build, and test vehicles like airplanes, helicopters, balloons, rockets, missiles, satellites, and spacecraft. Read more ( air-projects/science-engineering-careers/aero_aerospaceengineer_c00.shtml) Mechanical Engineer Mechanical engineers are part of your everyday life, designing the spoon you used to eat your breakfast, your breakfast's packaging, the flip-top cap on your toothpaste tube, the zipper on your jacket, the car, bike, or bus you took to school, the chair you sat in, the door handle you grasped and the hinges it opened on, and the ballpoint pen you used to take your test. Virtually every object that you see around you has passed through the hands of a mechanical engineer. Consequently, their skills are in demand to design millions of different products in almost every type of industry. Read more ( airprojects/science-engineering-careers/apmech_mechanicalengineer_c00.shtml) Credits Terik Daly and Michelle Maranowski, PhD, Science Buddies This science project is based upon the following Science Buddies Clever Scientist Award winning project: Agajanian, L. (00). Gauss Rifle Magnetic Linear Accelerator. Elmer's is a registered trademark of Elmer's Products, Inc.

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