I'm sure you've seen the broken surface of the wood, and there are a lot of thorns. Suffice it to say, I was impressed. Why does wood become like this when it breaks, and what is the reason for it? I looked at the wood and couldn't help but think a lot. However, after all, I have not systematically studied physics and do not understand mechanics. Therefore, there is no gain in it. However, I couldn't let go of it in my heart. Today the time has come and I feel compelled to discuss it. Remember that when you cut something, the cut surface is very flat. I thought that the knife is such an amazing thing that it can do this. Later, I studied physics and learned about the transmission of force. However, I still don't seem to understand the transmission of force. Guys, can you answer that question for me?

Mizukawa rice, it's good to be interested. If Newton wasn't interested in the apple landing, how could he have discovered the law of gravitation? If Watt hadn't looked at the lid, he wouldn't have improved the steam engine. If you're interested, you're already a big step towards success. Why did wood become like that? That's because the transmission of force is disordered, so the fracture surface is a shape with many fractals. Why is the cut surface of the knife cut object very flat? Because there are two slopes for the blade and the non-blade. It is these two slopes that give direction to the transfer of forces.

Liuzi Feng comes, how do you explain that the scimitar will get stuck when cutting bamboo?

This one is easy to explain. Although the transmission of force occurs, it is limited by other conditions. The first is hardness. The greater the hardness, the greater the breaking stress of the object. The breaking stress counteracts the pressure from the outside, so the fracture does not occur.

Liuzifeng, is the fracture stress point, surface or volume?

Point, of course. Otherwise, how to explain the fracture of wood? I think that when the breaking stresses at various points on an object differ very little, the transfer of force is largely reduced. In other words, the transfer of force is basically not carried out.

However, I think that when a kitchen knife cuts vegetables, the cut surface is not flat under the microscope. Can you say that this is not caused by the transmission of force?

Duenias, in fact, every object has a very small fractal. Of course, the same goes for knives. The fine fractal of the cut surface is caused by the fractal of the knife and has nothing to do with the transmission of force.

We noticed that the edge of the tab of the beer can was indented, which was what made it easy for us to pull the tab off the can. So, why does indentation make it easy to pull the tab up? The answer is that the indentation is different from the two sides of the indentation. In other words, there is a difference that allows the transfer of force to be carried out to the maximum. You say that every object has a fractal, so doesn't that mean that the object being cut has a difference in shape? In that case, why does the cutlass get stuck?

Margarita, fractals are small like microscopic particles, whereas objects belong to macroscopic things. Isn't it wrong for you to use Newtonian classical mechanics to explain quantum? Of course, fractals do allow a small part of the force to be transmitted.

I'll say something else. The malleability of the object also affects the transmission. If you cut the paper with a knife, you may not be able to cut it right away. What does this mean? The transfer of force is complete, but the force is dispersed and released into the air. When you cut the kneading dough, you will find that the dough has a certain malleability. However, it is not malleable enough to resist deformation.

After hearing this, all three said: Margarita said it well. Then, he turned and left.