Quote:
Originally Posted by KSagal
Okay. Lets take baby steps so that my limited understanding will not be overwhelmed.
I know that things in motion have a tendency to stay in motion, unless acted upon by another force. (If we continue to somewhat ignore things like friction, wind resistance, rolling resistance and the like, and roll them all toward a title I would call 'natural slow to a stop force'.
So, if you are rolling along and keep neutral, in other words, you do not motivate the segway to drive you forward, you will eventually stop.
However, if you want to stop sooner, you have to apply some energy into stopping...
Now, in a car, we have spoken of binder or friction brakes. But what has not been discussed is the mechanical or physical energy that goes into applying the friction to the brakes. Anyone with power brakes in an older car, who has tried to stop the car when the engine has stalled will know what I am speaking about.
Another example of a friction brake would be the hand brakes on a bicycle. Many of us have ridden, and know that our hand will get tired trying to slow down quickly at the bottom of a large hill. I have spoken in the past of a tandem Mountain bike that I have used in the past, with my wife behind me, a toddler in the trailer off the back, a baby in a bike seat on the handlebars, a large dog on either side on outriggers (dogs ran along either side). You can imagine that rig will roll down a hill and develop quite a bit of kinetic energy. To stop it with those bike brakes did generate some heat. But to keep the brakes on consumed a great deal of physical energy as well.
Now, with electrical brakes that apply force to counter act the kinetic energy that would keep the segway rolling for some distance, some energy must be consumed to enhance the natural forces that would stop the segway.
Again, to have a lot of speed, and stop it quickly, takes a larger opposing force, than to have that same speed and stop it slowly. (or more appropriately stated, the same force applied more quickly)
So, I wind up back at the 'things in motion have a tendency to stay in motion, unless acted upon by another force'. Does that other force not require energy?
I am not saying that the segway will not generate electrical energy as it slows down. What I am saying that to slow down quickly on command also consumes energy.
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I'll come back to the more general question later, but this part is easy.
The answer is "no, force does not require any specific amount of energy. Consider the energy required to drop in a pin in a slot to lock the wheels. It can be trivial."
Your experience confuses force and energy, and is based on how old brakes were designed (not very well), and not any real physical requirement.
It takes no energy to just apply a force. Energy is force TIMES DISTANCE. That is, you keep applying that force as you move something (or you are moved) through a distance. But to apply a force over zero distance consumes (and produces) zero energy. Our muscles are inefficient, they tell us otherwise because they waste energy when generating a force.
I'll come back to that when I get a chance to explain the overall picture more.