Which detail about an axe lets you know that it is a wedge?

Options

A. It has just one inclined plane.
B. It changes the way work is done.
C. It has two inclined planes.
D. It changes the direction of the force applied.

Explanation

To determine which detail about an axe indicates that it is a wedge, we can analyze the characteristics of a wedge and how they relate to the design of an axe.

### Step-by-Step Solution:

1. **Understanding Wedges**: A wedge is a simple machine that consists of two inclined planes joined back to back. It is used to split, cut, or lift objects.

2. **Analyzing the Axe**: The head of an axe is designed to cut through wood. When you look at the head of the axe, you will notice that it has a sharp edge that tapers to a point.

3. **Identifying the Inclined Planes**: The sharp edge of the axe head can be seen as having two inclined planes that meet at the edge. This design allows the axe to exert force on the wood, splitting it apart as the axe is driven into it.

4. **Comparing Options**:
- **Option A** states that it has just one inclined plane. This is incorrect because an axe has two inclined planes.
- **Option B** mentions that it changes the way work is done. While this is true, it does not specifically indicate that it is a wedge.
- **Option C** states that it has two inclined planes. This is correct and is the defining characteristic of a wedge.
- **Option D** suggests that it changes the direction of the force applied. While this is also true, it does not specifically identify the axe as a wedge.

5. **Conclusion**: Based on the analysis, the correct detail that indicates that an axe is a wedge is that it has two inclined planes. Therefore, the correct answer is **Option C**.