Any of you physicists have any theories on why the results are what they are?

I'm calling bullshit on this. I clicked lower for the spinning block. It didn't say how much lower, just lower. And in the final comparison video the difference is slight, but the spinning block is lower.

They have a theory they're trying to push, but the video doesn't support this. Like I said, it's not a huge difference, but it's there, and they're wrong.

To see this more clearly you can see in the high speed footage that both shots happen at exactly the same time. So if they both go to the same heigh they would both fall at exactly the same time. But if you stop the video when the non spinning block lines up with the glass on the way down you'll clearly see that the spinning block is well past that point, it clearly overlaps the glass. It could only do this if it had not reached the same height as the other block.

Essentially my guess is that the bullet can only transfer so much kinetic energy to accelerate the block upwards. Above that threshold it finds other ways of disposing of this energy. Why this threshold/diminishing return might exist idk.

So yeah, I think there must be some change in the efficiency of the transfer of energy in the two examples. Does smacking the bullet right in the centre create more sound? Does the bullet deform/heat up more in the first example because the block simple can't get out of the way fast enough? You'd think that spinning a block would take comparitively little energy compared to all those other inefficiencies. Perhaps if you were to increase the velocity of the bullet you might not see that large of a difference in the height it rises - rather the block would sustain more damage, the slug would pancake more etc etc.

It does seem raher counter-intuitive though. I'd like to know the explanation.

Without a solid background with proper measurement lines I think it's hard to say if it was the same. However I would have expected a larger difference, so they still came fairly close.

I think we'd need to see the experiment repeated a few times to ensure we get a constant result. And done under more controlled conditions (background marked better to make more accurate measurements, indoors to minimize wind, etc.) and high speed cameras watching the impact zone to watch the bullet closely. Also did he use the exact same type of wood both times? Did he actually pull a fast one on us? So many variables.

I also figured it would be lower because, well, physics. I think the spinning block was ever-so-slightly lower, but they were so close, practically millimeters it seems, that I am still curious about the lack of a greater difference.

The only thing I could think of that would cause this is that the initial rate of angular rotation on the spinning mass made up for the lower amount of direct kinetic energy from the bullet.
The bullet still conveyed the maximum amount of potential kinetic energy, but instead of transferring it solely to the objects linear acceleration, it transferred half to the objects linear acceleration, and the rest to the objects rotational acceleration, and by some principle of centrifugal or centripetal force that rotational energy somehow caused the block to reach the same height.

A shot in the dark, but that's my guess.

Assuming that the energy required to make it rotate is significantly less than that required to travel upwards against gravity.

I would think that the CG of the spinning block did in fact not go as high, but you can't easily tell because it's only a tiny amount lower, and that tiny difference went into rotation.

-scheherazade

It takes energy to deform/compress the block in order to make room for the bullet. I think the bullet travels further into the block when it hits head on. When the bullet hits off to the side, some of the energy is able to be spent on rotating the block instead of compressing the block.

conservation of linear momentum?