# Magnetic Linear Accelerator Science Fair Project

Instructor: Amanda Robb

Amanda has taught high school science for over 10 years. She has a Master's Degree in Cellular and Molecular Physiology from Tufts Medical School and a Master's of Teaching from Simmons College. She is also certified in secondary special education, biology, and physics in Massachusetts.

In this lesson, you'll be learning how to build a magnetic linear accelerator. By the end of the project you should have a deeper understanding of the magnetic force and how different forces affect the motion of an object.

## Introduction

 Goal: Build a magnetic linear accelerator to launch a steel ball Age: Middle school and up Safety Concerns: Neodymium magnets are very strong and should be kept away from electronics. Wear safety goggles when launching your accelerator. Never launch a projectile near any people or animals. Use caution when cutting the tape with the precision knife. Time: One hour

Imagine getting on a roller coaster. It's one of the fastest ones in the park and accelerates you up to 100 miles per hour! A little nervous, you look around and notice there's no enormous hill in front of you. How will you gather the momentum to reach such great speeds if you start from a flat surface? The answer is a magnetic linear accelerator.

Magnetic linear accelerators rely on the strength of opposing magnetic fields to propel objects forward at great speeds. In the case of this type of roller coaster, magnets on the ground and on the outside of the cars repel each other, causing the cars to zoom forward along the track. For a review on magnetic force before we begin, you can check out this lesson: Magnetic Force: Definition, Poles & Dipoles. Instead of using gravitational potential energy stored in the height of the first hill, these coasters use the force generated by magnets for their source of kinetic energy.

Today, we're going to build a model magnetic linear accelerator that will launch a small steel ball similarly to how roller coasters are launched around a track with this technology.

## Materials

• Wooden ruler with a groove in the center
• Tape
• 9 steel balls about 5/8'' in diameter
• 4 neodymium magnets that fit on the ruler, about one inch squared
• Safety goggles
• Precision knife

## Steps

Safety Tip!! Keep neodymium magnets away from electronics and use caution when handling a precision knife.

1. Place one magnet about 2.5'' away from the end of the ruler directly over the groove in the center. Tape it into place and trim any excess tape from the edges with the precision knife.

2. Repeat step 1 with the next three magnets, placing each one 2.5'' away from the previous magnet.

3. Now, place two balls on the inside of each magnet in the ruler groove.

4. Put your safety goggles on.

Safety Tip!! Be careful when launching projectiles. Always aim projectiles in an open area away from people, pets, and breakable things.

5. Place the last steel ball in the groove of the ruler before the first magnet and hold it in place at the end of the ruler.

6. When you're ready to launch, let the first ball go.

## Trouble Shooting

Make sure you have measured the correct distance between your magnets. If the magnets are too close or too far away, there will be changes to the magnetic force that can affect the motion of the balls.

## Discussion Questions

Why did the balls shoot forward when you launched the one you were holding?

How do you think adding more balls or magnets would affect the experiment?

Where did the energy needed to launch the balls come from?

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