During the holidays, a classmate assisted his mother in cooking in the kitchen, and he became intere

The smaller the force area, the greater the pressure.

Because of the same pressure, the smaller the contact area, the easier it is to concentrate the force in one place and cut through the object.

The smaller the apex angle, the sharper it is, in other words, the greater the pressure.

When the pressure F is applied on the split back, two components F1 and F2 of the vertical side are generated, and other objects that are processed are separated by relying on these two components in use Knowing by symmetry, the magnitude of these two components is equal (F1 = F2), so draw the parallelogram of force decomposition, which is actually diamond-shaped, as shown in Figure C

In the parallelogram of this force, take a quarter of it (shaded in the figure), and according to its similarity to the right triangle of half a split, by the relation, we get F1 = F2

It can be seen that when a certain pressure F is applied to the back of the knife, the force of the side to separate other objects is related to the magnitude of the apex angle, the smaller the apex angle, the smaller the value of sin, and the greater F1 and F2

However, the smaller the top angle of the blade, the strength of the blade will decrease, and the blade will roll up or even shatter when encountering a harder object, in order to meet the needs of processing different objects in the actual manufacturing process, it is made into a thinner front and a thicker rear When using, use the front to cut some soft items (such as fish, meat, vegetables, fruits, etc.), and use the rear to chop hard bones and other items, as the saying goes: "cut before and then split", which refers to this meaning Therefore, D is correct

Therefore, D