Extreme Science: Penny Shine

What you will need:

  • (12) Round fishing weights with eye loop on top (called Bullet weights)
  • Fishing line
  • ½” PVC pipe(about 5 ½ feet)
  • (2) ½” 3 way PVC connectors
  • (4) ½” PVC 45 degree connectors
  • (4) ½” Rubber stoppers
  • Piece of wood 20” x 2”
  • Glue gun
  • Drill
  • 1/8” drill bit
  • Small sewing needle
  • Tape
  • Adult supervision


  1. Cut your PVC pipe to the following lengths:
    4 pieces @ 12”
    1 pieces @ 18”
  2. On your 18” PVC pipe, drill (11) 1/8” holes 1 ½” apart starting 1 ½” from one end as shown.  The last hole should end up 1 ½” from the other end. Holes need to be drilled all the way through the PVC pipe and out the other side.
  3. Place a 3 way connector on each end of the 18” PVC pipe as shown.

  4. Insert the four 12” legs as shown.

  5. Place a 45 degree connectors on the end of each leg as shown.

  6. Insert rubber stoppers into bottom of each leg as shown.

  7. Feed your fishing line onto a sewing needle and use this to run the fishing line through each hole.  Make sure to leave extra line on each section, which can be adjusted later.  I found it was best to wrap the line around the PVC pipe and use a piece of tape to temporarily hold it in place.

  8. Add the weights to each line by threading the looped end of the line through the eyelet on the fishing weight, then feed the weight through the looped line and pull on weight to tighten line against the eyelet as shown.

  9. Once you have all of your weights installed, you will need to adjust the length so that each one is slightly shorter than the one next to it from one end to the other.  I found that it is easiest if you prop something up at an angle underneath the weights so that you can adjust the length so that they are just barely touching your guide.  Make sure that each one is evenly spaced and hanging straight down and not pulled off to one side or the other.  Once they are all adjusted, add a small amount of glue (using your hot glue gun)  to each line to keep them from moving.

  10. Use your 20” x 2” piece of wood to hold all of the weights to one side by propping it on the legs closest to you.  Slide the wood down to release all of your weights AT THE SAME TIME.  Now you can watch as the weights begin to make several really cool patterns as they swing for the next several minutes

What is going on?

Gravity is the force that holds us to the surface of the Earth.  When you drop something, gravity pulls it downward towards the Earth.  By connecting your weights to strings and attaching the strings to the top piece of PVC pipe, you have now created what is called a pendulum. A pendulum is a weight that is suspended from a pivot so that it can swing freely.  Pendulums will oscillate back and forth past their resting position due to their mass and gravity.  The time that it takes to swing all the way over and back is called the period.  The period depends on the length of the pendulum.  Since each pendulum is slightly longer than the one next to it, the period in which each one swings will be slightly different.  This is what causes the patterns to form.  Count how many different patterns you can see when you swing your pendulums.

Radical Rick

Extreme Science





Recommended for you