- Yes.
- You need to solve two problems.
First, given the natural radius of the spherical membrane $R_0$ (the radius with no tension in the membrane) and the current membrane radius $R$, membrane's modulus of elasticity $E$ and Poisson's ratio $\mu$, calculate tension stress in the membrane. If you consider an infinitesimally small square (with the side of $\delta l_0$) of the spherical membrane under no tension with thickness $d_0$, currently it will be a square with a side of $\delta l=\delta l_0\frac{R}{R_0}$. The tension stress $\sigma$ will expand the square in two directions. Calculation of tension stress from strain (using elasticity modulus and Poisson's ratio, and assuming the membrane material is isotropic) is a standard task, see e.g. https://en.wikipedia.org/wiki/Poisson%27s_ratio , although you may wish to find a better source. The exact value of the Poisson's ratio is not very important.
Second, given tension stress, calculate differential pressure in equilibrium. To do this, consider the condition of equilibrium for a half of the spherical membrane: $(p_i-p_o)\pi R^2=2\pi R d\sigma$ (assuming the membrane is thin: $d_0<<R_0$).
The basic physics of the throw is momentum and the lever. You encourage your opponent to topple over, pivoting about the ground and your hip. At the same time you limit his options for evasive action. As long as your opponent is passive, unable to use his strength, it makes little difference that he is much stronger or much heavier than you.
Your opponent could be modelled as a tall column. To make a stationary column fall you pull or push high up, as far as possible from the pivot. The higher up you apply the force, and the lower down the pivot, the less force you need to use. Ideally the pivot is at the ground : you use your legs and hip to prevent your opponent moving his/her feet forward. The fact that the knee does not bend backwards means that the thigh has to move forward to get the foot forward, and your hip should obstruct his thigh.
It is easier to topple a column with a narrow base than one with a wide base. So you pull your opponent forward, where the base is one foot wide, instead of to the side, where the base is much wider if the legs are spread defensively.
If possible you time your throw when your opponent is moving towards you, to make use of his forward momentum and lack of a defensive posture. Walking can be described as continuously falling forward, pivoting about each foot in turn. With an unwary opponent, his momentum and weight do almost all the work. It is only in competition with an experienced opponent that you need to exert much force. See Problems hip-throwing a larger opponent.
The purpose of the thrown is not only to get your opponent on the floor but also onto his back where he is (presumably) more vulnerable. To do that you have to roll him over your hip. It requires the least amount of effort to do this if your hip is just below his centre of mass. Just below means that his weight and forward momentum create a torque which keeps him turning in the right direction.
If your hip is too high you will need to use more effort to lift your opponent over, and the difficulty will increase as the opponent is heavier. If your hip is too low you will not be able to prevent him from flexing his knees to bring his body low to avoid falling forward. Also, any force you exert on your opponent's arms from this position will be downwards, almost through the pivot, so it will have less turing effect (torque). See When doing a hip throw is there such a thing as too low?
A hip throw could fail if you allowed your opponent enough space to plant a leg forward to resist toppling or to flex his knees and drop towards the ground, lowering his centre of mass below your hip. Even with a passive 'opponent' which does not flex at joints, if your hip is too far forward the 'opponent' will make contact with it higher up, above its centre of mass.
Best Answer
Is a nice design, although it seem rather complex it only has one degree of freedom related to the expansion.
So it is a ingenious ensemble of pieces that are connected to each other in such a way that the system is only stable in 2 configurations.
Is composed of two types of pieces:
disc-like piece: there are 4 of them visible for each color, they are surrounded by 3 of the other type:
foil-like: they surround each disc-like piece when the ball is contracted
Going from one configuration to the other involves the hiding of 4 disc-like pieces, the surfacing of the other 4 that were hidden inside, and the flipping of all the foil-like pieces.
Why does this happen when rotating? Well this is caused by the centrifugal forces created when to the ball rotates. And it does not matter the direction of the rotation because when you pull one piece outside to expand, all the pieces move together due to all their movements being coupled. That is what it means that it has only one degree of freedom.
Why does it contract again? Well the ball can only expand certain amount due to its design, at this point it bounces back and starts a contraction movement folding again.
The details of the design are rather out of my design-drawing skills and I did not find better images or diagrams of the actual toy to produce here. I hope the explanation was graphic enough.