Laser-cut design components for a Newton's cradle/Gauss gun
See assembling instructions at https://youtu.be/IWAIx6-hRZI
For an overview of Gauss guns (and a video of them shattering 3 glass light bulbs) see https://youtu.be/nWyTd7dF0ys
Project designed to help young students learn about energy and its role in creating motion. Energy cannot be created nor destroyed, but it can be transferred between objects and from one form to another. In this case the Newton's cradle and the Gauss gun are the devices used to show how gravity and magnetism (potential energy) help things move (kinetic energy), and how energy, and thus motion, is transferred between objects when they come in contact.
Designed by ECE undergraduate Javier Garcia, advised by Aaron T. Becker at the University of Houston.
The purpose of this project is to demonstrate several forms of energy transfer. The model has two configurations, which are achieved by simply rotating the leg supports. When the curved faces are pointing up the model is in the Newton’s cradle configuration, and it demonstrates the transfer of gravitational potential to kinetic energy. Some balls are placed on the valley and another is placed on one of the higher sides; as the ball rolls down towards the valley it gains speed due to gravity, and when it hits the balls resting its momentum is transferred to the last ball on the opposite side, making it move. Another concept that can be explored here is energy dissipation, primarily through friction, as it can be easily noted that the balls don’t make it all the way to the top again.
When the channels are pointing up the model is in the Gauss gun configuration. In this case, a magnet is placed midway along the channel and several balls are attached to only one side of it. Another ball is placed on the side of the gun where there’s nothing attached to the magnet and it’s given a little push. As the ball approaches the magnet its speed is greatly increased, since it’s made out of magnetic material, and as a result when the ball hits the magnet the last ball on the opposite side is sent flying. The lesson here is that the ball that is initially in movement achieves more speed and therefore carries more energy in the Gauss gun than in the Newton’s cradle, thanks to the magnetic potential being greater than the gravitational potential. To better transfer momentum through the balls the magnet is set in a slot to prevent it from moving when the ball impacts, and the model is designed so that multiple Gauss gun stages can be connected to shoot balls at even higher speeds.
After this project students will have a better understanding of the concept of energy and one of the ways it affects objects (motion). They will also better understand how energy is transferred between objects, and transformed (from potential to kinetic energy in this case).
Ask students how devices such as cellphones, cars, appliances, etc. work. Lead them to realize that charged batteries, fuel, electricity from the wall outlet, etc. transfer "something" to the devices in order to make them function. Discuss with them that the "something" is called energy and that energy that is initially stored in one form can be converted to another form in order to produce a change, such as a screen turning on or an object being set into motion.
Activity 1: Newton's Cradle
Distribute the model sets to the students. It is recommended to not give them the magnets at this point, since it will very likely cause distractions. Tell them how to assemble the model in the Newton's cradle configuration. After they are all done, tell the students to place one ball on one of the sides of the cradle and let go of it. Ask what they think is causing the ball to roll down towards the valley of the cradle. Discuss with them that gravity gives objects the potential to move, giving other examples such as lifting a pencil and letting go of it. Make them realize that as the ball rolls down its speed increases, and that this means that the energy due to gravity is being converted into "motion" energy, which is called kinetic.
Afterwards tell the students to place about 3-4 balls in the valley of the cradle and let a ball roll down from one of the sides again. When the moving ball hits the resting balls, the last ball on the opposite side will start moving; discuss that the kinetic energy from the ball rolling down is transferred all the way to the ball on the opposite side when it collides.
At this point you can also mention that the second ball in motion doesn't reach the top of the cradle, and that all the balls come to a rest after a while. Ask the students why they think this is the case. Discuss that energy must be leaving the system due to mechanisms such as friction. Mention that friction transforms kinetic energy into thermal energy, or heat. Ask students if they can think of other examples that demonstrates such transformation.
Activity 2: Gauss Gun
Tell the students to put on their safety glasses and assemble the model in the Gauss gun configuration. Distribute the magnets and have the students discuss for a couple of minutes how they think magnets work. Afterwards, have them place the magnet in the slot in the middle of the gun channel and to put 3-4 balls on one side of it. Tell them to make sure that the balls are aligned and centered, and that no one is right in front of the side of the gun where the balls are. Once that's done they have to hold another ball on the opposite side of the channel, away from the magnet. Tell the students to pay close attention to what happens when the ball is given a little push towards the magnet.
After shooting the gun a couple of times, ask them why the ball on the opposite side gains so much more speed compared to the Newton's cradle. Discuss that magnets, just like gravity, give objects the potential to move. Such form of energy is called potential energy, because it's stored in objects and it's transformed into kinetic energy when the objects are released. Also discuss that the magnetic potential in this case is greater than the gravity potential, giving the ball much greater speed as it approaches the resting balls, which explains why the ball all the way in the opposite side gets so much more kinetic energy transferred to it.
If there's time, show the students how to connect multiple Gauss gun stages. The balls will shoot farther; discuss that multiple stages give the balls more speed which equals more kinetic energy.
Bill of materials for 12 Gauss Gun V2 sets
Build instructions for Gauss Gun V2