SOLENOID LAUNCHER

Length of Project:
Project theme:
Suitable for grades:
INSPIRATION
Catapults and slingshots have been used for thousands of years to fling objects with greater distance than a human’s ability to throw them. Modern versions using electrical technology can even shoot jets into flight from aircraft carriers. How far and fast can an object be launched using a simple electric launch system? How do solenoids work, and could they produce enough kinetic energy to fling an object? How can mathematics help us describe the path of a launched object?

OBJECTIVE
Students will experiment and build their solenoid launcher to fling a tiny magnet, then use its resulting motion to explore how quadratic functions describe parabolic flight.

TRADES CONNECTION - TOOLS
Auto-mechanics, heavy duty mechanics, and plumbers are trades people that work to install and use solenoids as tools every day. For example, in heavy duty equipment, solenoids are used to control the flow of hydraulic fluid through hollow lines to control the articulation of machinery. Using hydraulics, tiny solenoids in combination with fluid lines and simple machines can control enormous systems.

RESOURCE DOWNLOADS
Electrifying Math: Introduction and Glossary
Scientific Method Resource
Tools & Materials
Material List
  • Magnet Wire, 18-30AWG, up to approx. 12m
  • 9V battery
  • 2 insulated connector wires with alligator clip ends
  • One ¼” neodymium disc magnet, or a similar strong tiny magnet
  • Scrap paper or cardboard, approx. 3cm x 10cm
Tool list
  • Scissors
  • Pencil or pen permanent marker or found cylindrical object slightly larger than magnet’s diameter
  • Jar or mug
  • Clear tape
  • Electrical tape
  • Wire cutters
  • Sandpaper
  • Measuring tape, meter sticks, sewing tape, etc.
  • A digital camera or smartphone capable of recording slow motion footage
  • Stopwatch
  • Protractor

    • Optional:

  • Demo tools (batteries, assorted wires, resistors, magnets, and a class set of magnetic compasses)
  • Multimeter
  • Variable DC power supply
  • Laptops or desktops to view video footage on a large screen
Procedure
  1. Place your spool of magnet wire on a pencil and balance it over the rim of a mug or jar to help it pay out.
  2. Leaving a 10 cm tail, use a small piece of clear tape to fix your wire to the side of the permanent marker/found cylindrical object. Make tidy wraps coiling up the marker in a tight helix, periodically pushing the coils down to sit tightly together.
  3. When you have about 3 or 4cm of coil wraps, lay a small strip of clear tape over the wire wraps to secure them, and wind another layer of wraps down over the first layer.
  4. Lay another small piece of clear tape down to secure the second layer of wraps and begin coiling the wire again in the opposite direction.
  5. After you have used approximately 12 metres of wire, or have done 4 layers, wrap the coil completely in one layer of clear or electrical tape to keep its cylindrical shape.
  6. Snip the wire, leaving another 10cm tail.
  7. Use sandpaper to strip the insulation off the last 2cm or so of each wire end, then remove your coil (solenoid) from the marker. You may need to peel up the clear tape and snip it away with scissors to free the solenoid.
  8. Make a small triangular prism using some scrap paper or cardboard and tape. Affix your solenoid to the prism, so one solenoid end touches the table and the other rises at an angle. Secure this assembly to the tabletop with tape.
  9. Clip one connector wire to the 9V battery and the other to one wire end of the solenoid.
  10. Clip a second connector wire to the free wire end of the solenoid.
  11. Place the neodymium magnet on the table at the base of the solenoid. To launch the magnet, briefly touch the free alligator clip to the free 9V battery terminal. Do not leave the clip in place, just touch the terminal quickly and remove it again.
  12. Play with the magnet’s position and orientation (as well as the lenth of time you connect the circuit) to get the magnet to launch through the solenoid.

    13. TROUBLESHOOTING:

  13. Is the magnet getting stuck in the solenoid instead of launching? Try touching the battery terminal for a shorter length of time. (If the electricity remains on, the magnet is held in the center of the solenoid and does not shoot out with the momentum it gained in the first half of the solenoid).
  14. Experiment with which side of the battery faces up before launching. You may want to indicate one side by sticking a tiny piece of electrical tape to one side.
  15. Is the solenoid too wide? Try rewrapping the solenoid on an object with a smaller diameter.
  16. Do you want to power up the launcher? You could try adding more voltage, or more wraps, etc.
Extension Challenges
  1. Challenge students to design a launcher that shoots a ping pong ball and utilizes a hobby motor.
  2. Give students some independent variables to play with, such as magnet diameter, strength, etc., and predict how the trajectory path would be affected. Students develop a hypothesis regarding the flight path of the magnet and design a scientific procedure to explore their idea. Get them to analyze their quantifying data using statistical calculations (central tendency, standard deviation, confidence intervals, z-scores, and distributions).
  3. Discuss with the class the phenomenon of achieving the greatest horizontal distance of the magnet with a 45-degree launch angle from the launcher. To hit a target any closer, you have TWO different launch angle options: sends the magnet low and more directly into the target and one that sends the magnet higher in the air first. See if students can determine the two angles of launch and then explore the phenomenon of those two angles adding up to 90 degrees every time!
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