Yes, it is simple physics (and basic maths).
What would the length of the torture stake be? Well if someone’s hands are to be nailed above their head, you need 2 metres. To have them on public display and out of reach of help for hours on end, you would need 2 to 3 metres more. (Let’s just say 2m for argument). Then you have to bury the base. The base needs to be long, as the load is unbalanced (hanging to one side) and the victim might potentially shake the stake with convulsions. If it is in hard rocky ground, and rocks wedged in afterwards, you might get away with just 1m. Anything else, you would need 2m. I would estimate longer because the Romans wouldn’t risk the embarrassment of a flopped execution. But let’s go with 1 m anyway.
That totals 5m minimum (and in reality, more likely closer to 7m.
The stake diameter would have to be at least 300mm, for strength, to enable nails to hold without splitting the timber, and because it would be difficult to get a straight length that long that is any thinner. In fact, it was probably wider than that, at least at one end.
Approx weight (assuming density of 1000 kg per cum):
5 x 1000 x 0.3 x 0.3 x 3.14 / 4 = 353 kg. Too heavy for a single person to lift at one end, let alone drag anywhere.