Marble Cannon

Building a cannon for physics isn't really what I thought I'd be doing this year, but here's how I did it.

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Step 1: Step 1: Get Supplies

I went to Home Depot to find all my supplies, but the workers didn't even know the way around so, maybe go to Lowe's instead. You will need:

  • A 2 by 4 (I got one of the ones that was precut at 4 feet)
  • A 1 by 4 (again I got one that was precut at 4 feet)
  • A 3/4 inch PVC pipe (precut at 2 feet)
  • A 3/4 inch wooden dowel (precut at 2 feet)
  • A 1/4 inch wooden dowel (precut at 2 feet)
  • Two tension springs (the ones I found were meant for doors)
  • A 2-inch door Hinge
  • A wooden baseboard
  • 45-degree wooden block (I made mine)
  • Zip ties
  • Hot glue gun (and glue)
  • Screws (most of my things came with screws, but not everything does)
  • A Sharpie
  • A drill
  • A hacksaw
  • A saw
  • Protractor

Step 2: Step 2: Cut Things Down to Size

Unless you want to make a massive oversized cannon you're gonna need to cut some things down to size. Cut the things down to the lengths listed.

  • 3/4 inch wooden dowel - 57cm
  • 1/4 inch wooden dowel - 8.25cm
  • PVC pipe - 45cm
  • Wooden board - 50cm by 30cm
  • 2 by 4 - 50cm (length)
  • 1 by 4 - 50cm (length)
  • With the excess of the 2 by 4
    • cut a square 8.25cm by 8.25cm
    • then cut from one corner to the other
    • this creates a 45-degree block

Step 3: Step 3: Assembling Your Cannon

  1. Heat up your glue
  2. Add glue up the center of your 1 by 4
  3. Attach the PVC pipe to it
  4. Use zip ties around the board and PVC to secure it
    1. Note that the PVC won't stay stuck to the board like this, but it will create a grove where the PVC pipe will rest when you go top shoot later
  5. Once that's dry and cooled, take off any zip ties that are lower than the bottom half
  6. Cut off any excess length on the zip ties that are hanging off all floppy
  7. Set this aside for now

Step 4: Step 4: Building the Base

  1. Take your wooden board and 2 by 4 and attach them to each other with 4 screws
  2. Place one screw in each corner to get it securely attached
    1. If you want additional support you could attach a screw in either side in the middle of the board
  3. Set this aside

Step 5: Step 5: Putting It All Together

  1. Screw your door hinge onto the back of your cannon
    1. do this so that you can open it to raise up and down when attached to the base
  2. Screw the other part of the door hinge onto the end of the 2 by 4
  3. With the protractor measure where different angles lay on the 2 by 4
    1. Do this while holding the 45-degree block under it as what would be holding it up
    2. Mark a line and label the degree measure at the front end of the wooden block
    3. I recommend every five degrees
  4. In the center of the top if the 45-degree block (the hypotenuse of the triangle) drill a hole through, about a quarter of an inch diameter so your small dowel can fit inside
  5. Taking the 45-degree block place it on the 2 by 4 with the front at one of your degree lines
  6. Mark a dot or line where the hole is on the board
    1. I just put a pencil inside of the hole and marked it that way
  7. Repeat this for all of your degree measures
  8. Drill the same size hole that's in your wooden block for all of your marks
  9. Label all of the holes with the appropriate degree measure
    1. I did these ones in sharpie so they were easily visible, whereas the other ones were done in pencil
  10. Write your name on your masterpiece and you're done

Step 6: Step 6: Do the Math

Using your data from firing find the time and initial velocity

To find time use the equation pictured above (yellow)

To find initial velocity use kinematic equations (orange)

I wanted to fill the table, so I also found the final velocity (red)

My work for my trials is pictured above

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