Tipping Ballerina Effect

[Cognisant]

I've been wondering lately, why can't stored energy be converted directly to kinetic energy? As-is we require some manner of medium to push against mechanically or a propellent to be ejected at considerable velocity, but surely there's a better way.

Lets do a little thought experiment, imagine a ball on a string being spun around so that travels in a roughly horizontal orbit, held there by centrifugal force inertia. Now if the string were to be shortened, decreasing the duration of the balls orbit, the ball will of course accelerate in accordance with the conservation of energy. In principal this is exactly the same as a ballerina pulling her arms in when she spins, thus accelerating her rotation, but what happens if said ballerina only pulled in one arm? Well common sense is that she'd fall over.

Notice anything?

Now imagine we have a centrifuge with two weights inside that can be pushed along individual tracks from centre to rim, by a small electromagnet at the rim's end. In this way the centrifuge can be accelerated by activating the magnets, thus pushing the weights towards its rotational centre; but what would happen if the weights didn't move in unison, what if at one end of the rotation (lets call this point 12 o'clock) the weights sit at the rim and at the other end (6 o'clock) it moves towards the centre. Hypothetically this creates a constant "tipping ballerina" effect, thus converting electrical energy directly into kinetic energy, i.e. the force that pushes/pulls/whatever the ballerina over is due to a change in weight distribution with both arms fixed at the same rotational velocity.

More likely than not I've overlooked something and I'm about to be told exactly what that something is, but that isn't the sole purpose of this thread, I also want to know what ideas you have for theoretical propulsion, or other mechanical physics.

 

[warryer]

What would you use something like that for? I'm picturing it being fixed to some bearings and doing nothing but create bad vibration. It's an interesting concept.

I am usually spending my time thinking about this kind of stuff. So heres an idea of mine:

Lets say you have a .22 cal gun. The gunpowder ignites causing immense pressure behind the bullet. I ran some numbers and discovered that the energy efficiency is actually very poor. So I thought, how can this be fixed?

My solution is the same idea as hydraulics. Take a low pressure source and exert it over a larger area. This will allow you to apply the same force as gunpowder at a higher efficiency. Of course more force = more acceleration = higher velocity in a shorter time. The problem with this is figuring out a way to capture this energy because I think it has to be done in two stages. Also to give you an idea using a starting pressure of gunpowder (assumed 40,000 psi) I could make a bullet go 12,000 fps (~2.3 mi/sec or ~3.6 km/s). Pretty insane huh?

I am starting on my senior project (mechanical engineering) and have to decide what it is I want to do. I don't think a gun is really suitable for this so, I will probably go with a temperature controlling suit. Makes you warm when its cold out, or cold when its hot out.

 

[Cognisant]

I'm picturing it being fixed to some bearings and doing nothing but create bad vibration.

But if this unbalanced inertial force is only pushing it in one direction wouldn't it be in effect a sort of inertial engine? Like I said before I'm probably way off here but I can't figure out where the balancing force comes in that prevents the whole thing from
Oh right I've got it now, I forget that the weight's inertial pull force is entirely dependant upon velocity, so even though the weights themselves would be experiencing disproportional inertial forces their effects upon the device itself would completely negate each other since they're travelling at identical velocities.

Damn, I've made an idiot of myself

 

[Agent Intellect]

Traveling at identical velocities? If they were spinning in a centrifuge, the weight moving further outside will decrease the velocity of rotation, thus maintaining the invariance of L in L=r*p (where p=mv or momentum and r is distance from point of rotation). As r becomes a larger value the momentum p would decrease. This is the same principle that explains why, as the moon moves further away from the earth, the earths rotation is slowing down.

 

[Cognisant]

Well I meant rotation speed... but hang on that's still wrong.

Gah I'm making a bigger idiot of myself