Experiment #002

Disclaimer: Ask your parent to be with you if you are under age. This experiment uses an edged-knife, a saw or serrated blade and deals with varnish, that may smell funny.



The experiment is medium-difficult and require few things. I have not run it myself so it is only a planned experiment.

The goal of this experiment is to get a value for something called a fricction coefficient. This is for the floater of the Gravitic Motor that goes inside the tube. It is the black cylinder represented in the figure on the right.

This number tells how difficult it is for the floater to start moving, how much water we will have to put in one of the columns so that it moves. 

Get your Research Notepad ready and grab a pencil and an eraser.

Making the floater. 

Alternative #1: Glue styrofoam sheets, making first a small box. Then carefully slice or carve it with a knife into a cylinder. Paint the cylinder with a white paint, and varnish it, so it gets real smooth. Get your parent to varnish it for you so you don't breath the fumes.

Alternative #2: Make a floater out of a soap bar. The floater is less likely to move, so there is a risk here.

Floater's mass. 

Measure the floater's mass with weighting scale. You will need one with good precision in grams. 

The idea is very simple, you will build a U shaped tube, placing a styrofoam floater inside the tube before closing the U. The tube should have the hole on the surface just as in the Gravitic Motor previously discussed, as well as a pin or hook fixed on the floater, so you can watch the floater's motion. You should use a saw to make the hole before assembling the tube, and ask your parent to cut the hole. Do not atempt to do it by yourself, kid! 

TO PARENTS: Cutting the hole is why this experiment is medium-difficult. PVC pipes are rigid, and not very easy to be cut, particularly on the surface (not along the cross section). Preferably use a blade as show in this video. You can try using a serrated knife too.

Dimensions on figure are mere suggestions.

Grease or oil the floater, moving it back and forth a couple of times. Fill the tubes with water up to a level on both sides, so that the floater is standing in the central position. Don't fill the level too high with water.

Using a dropper (like the ones used for medicine), count the number of drops you can drop in one side before the floater moves. Register this number. 

If the floater does not move at all, then the friction is too great. It would take a taller column than what we have. We did not suceed I'm afraid, it can happen. Part of life is accepting that sometimes things don't go as we plan. Do not be discouraged, perhaps make a second attempt with a taller U. 

However if the floter did move, we can proceed with the Experiment Analysis.

Experiment Analysis

Water density at 23°C was taken from here.

Make sure to log your findings in your Research Notepad, and leave a comment with your results if you like!

Additional Considerations

This experiment was proposed because it is a simple way to test many aspects of the Gravitic Motor, before commiting to actually build a large one. It tests the workings of the floater, and should reveal any unforeseen behavior or difficulty. It also estimates the friction coefficient, an important parameter to know about in Gravitic Motors. The results are only valid for the styrofoam floater or soap bar floater, respectively.

The next section describes a full fleged prototype of the Gravitic Motor known as Phoenix.   

BANNER IMAGE CREDITS: ESA/Hubble & NASA, A. Filippenko, R. Jansen 

Want to know more about this image? Follow this external link.

The Dino from the KIDS Banner was taken from here.