Which is best, a paper hinge or a hinge balancing on a knife edge. There’s only one way to find out. Experiments!

I’ve put together three pendulum in box experiments. One with a paper hinge, one with a card hinge and another where the edge of a triangular tube is resting against the side of a box like a knife edge. I then set the pendulums a-swinging to see which would run for the longest. Bet you can’t guess which worked best!

If you are a member you can download the parts and try the experiment for yourself. Print the parts out onto thin card (230 micron /67 lb) Score along the dotted lines then carefully cut out the parts then follow the instructions for construction below. Scroll to the end if you can’t wait to find out which was best.

There are two slightly different layouts for the two designs. You’ll need two of the first page and one of the second page to make both types.

The first instructions are for the paper hinge pendulum. There are red circles on the parts specific to this model.

Cut out the hole in he top of the box following the black line. You can see clearly on the picture below right where the hole is. Fold up the flaps on the sides of the box to make right angled triangle sections as shown above.

Make up the triangle stiffener piece with the red circle and glue it next to the hole so that it runs underneath where the blue lines are.

Glue the box ends into place.

The knife edge box is slightly different. Cut out the hole on the top to include the area surrounded by the blue line and cut out the two slots outlined in blue. Glue the two longer triangle pieces long ways along the underside of the box as shown.

Complete the box in the same way as the other one.

Assemble the hinge as shown above and add coins to the end. The weight on the coin is not critical so long as they are the same on both models. I used UK 2p coins, roughly 7 grams each.

Assemble the second pendulum as shown above, this time adding a hinge made of the material of your choice. I tested paper and card.

Fit the pendulums into place and start them swinging. Which will run the longest?

In mine, the paper hinge was slightly better that the knife edge. That really surprised me. It was close though with one at 75 seconds and the other at 68 seconds. My other test, with the card hinge ran for only 20 seconds.

Let me know what you find out!