Here's why:

* Wedge: A wedge is a simple machine that is essentially two inclined planes joined at their bases. It is used to split, separate, or lift objects. Examples include axes, knives, and chisels.

* Inclined Plane: An inclined plane is a flat surface that is at an angle to the horizontal. It makes it easier to move objects up or down a vertical distance. Examples include ramps and stairs.

How a moving sloped surface works like a wedge:

When a sloped surface moves, it effectively acts like a wedge. The motion of the surface combined with the angle of the slope creates a force that can push or lift objects.

Example: Imagine pushing a box up a ramp (inclined plane). If the ramp is moving upwards, the box will be pushed upwards as well. This combined movement of the ramp and the box is similar to how a wedge works.