### Ripstik redux: teaching an old dog a new trick

With the intent of using the RipStik® as the centerpiece to a discussion of kinetic and potential energy in physical science next term, employing it's unique ability to climb an shallow incline, I have hired an professor of RipStikology to teach me the Zen of castor board riding. His over six months of RipStiking place him among the senior tenured faculty of castor boarding on this island. His skills have grown greatly since last August when he gained his own board.

Note on the right above the perfect placement of my professor's center of gravity over his wheels, his poise, his bent legs in an optimal position to control the board. Note the student on the left, clearly off-balance and completely clueless, about to do a face-plant into the concrete.

The student, just before he went backwards onto his derriere off the RipStik. The learning experience was interesting. My teacher kept noting the wrong placement of my feet, sounding just like I do when I explain to students that the placement of the term is incorrect in an equation. A real role reversal in the household.

I am not alone in my thoughts of using the RipStik in a science class. A young man in Mexico wrote to ask, "I'm an student from Mexico and I have to do a proyect about the Ripstik Caster Board, I read what you wrote about the Ripstik and the convervation of momentum? Would you have more information I can use for my proyect?"

Exactly how a lateral kinetic energy is converted to forward kinetic energy appears to be subtle. The force transfer mechanism appears to be similar to the basic beginner's ice skating maneuver called "swizzling" or "swizzles".

A Wikipedia article on caster boards, that is in need of some citations, argues that potential energy is being traded for forward kinetic energy. Whatever is actually occurring, the physics is fascinating. A skateboard-like device that can climb a slope, that can gain potential energy, and is not relegated solely to be purely gravity driven.

Conservation of momentum is involved, but only in that once the board is moving forward, the board tends to remain in forward motion.

There is plenty of room for speculation, a chance for young minds to roam, as in one explanation that angular momentum is involved.

Of course, to use the board in class, this old dog has to learn to ride. If nothing else, falling here is seen as greatly embarrassing, a cause for much amusement and laughter, all to my benefit in connecting with the students.

All of my children are talented. Some just have more unusual talents, such as facial alterations with rubber bands.