Make Your Own KINETIC ENERGY MACHINE with PHYSICS in Minutes

ROLLBACK CAN EXPERIMENT
Make Your Own KINETIC ENERGY MACHINE with PHYSICS in Minutes
Made for parents and teachers

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Chapters
0:36 Rollback can experiment
0:45 Science behind this experiment
1:48 What you need for this experiment
2:16 How to put it together

What you need:
(2) 6" paper plates
(3) #64 Rubberbands
(4) Washers
(2) Craft sticks
(1) zip tie 6"
(3) Large paper clips
(1) Correlated cardboard piece 6" x 17"

The Science Behind the Rollback Can

A lot of the moving energy from pushing the Rollback Can gets stored in the twisted rubber band. This stored energy turns back into moving energy as the rubber band untwists. The thin edges of the can help it roll with less rubbing, so it can come back almost to where it started on a flat surface.

The weight inside the can gets pulled down by gravity. If the weight doesn’t lift up and go over the rubber band, the band twists tighter and tighter as the can’s ends spin. This happens after you give the can a little push or roll. The twisting rubber band saves up stretchy energy. At some point, all the moving energy turns into this saved energy and a bit of rubbing. When all the moving energy is gone, the can stops going forward (that’s when things are even, with no extra push).

The rubber band puts a twisting push on the ends of the can and the weight in the middle. Only the ends can spin if the weight can’t be lifted over and around the rubber band. The saved energy in the twisted band gets let out as the can spins the other way, moving back to the start (that’s when things are uneven, with extra push).

Sometimes the rubber band gets twisted so tight that the weight lifts up and spins around the band in the other direction, untwisting it. Some of the saved stretchy energy turns into moving energy for the spinning weight, so the can won’t come back quite as close to the start if the weight stays below the twisting rubber band.