There are some steel balls in an iron box. They will behave

Options

A. like a non-rigid body, because the material of box and balls is different.
B. like a non-rigid body, because the balls in the box are not stuck at a point.
C. like a rigid body, because the box and the balls are rigid bodies.
D. like a rigid body, as the box and the balls are solids.

Answer

To solve the question regarding the behavior of steel balls in an iron box, we need to analyze the properties of rigid and non-rigid bodies.

### Step-by-Step Solution:

1. **Understanding Rigid Bodies**:
- A rigid body is defined as an object in which the distance between any two particles remains constant, regardless of the forces acting on it. This means that the shape and size of the body do not change.

2. **Identifying the System**:
- In this scenario, we have steel balls placed inside an iron box. Both the steel balls and the iron box are made of solid materials.

3. **Analyzing the Behavior of Steel Balls**:
- When the box is stationary, the steel balls may appear to be at rest. However, if the box is shaken or moved, the steel balls will move around within the box. This movement indicates that the distance between the balls can change.

4. **Conclusion on Rigid vs Non-Rigid**:
- Since the distance between the steel balls can change when they are in motion (i.e., when the box is shaken), we conclude that the system of steel balls in the box does not maintain a constant distance between its particles.

5. **Final Answer**:
- Therefore, the correct option is that the system behaves like a non-rigid body because the balls in the box are not stuck at a point, and their relative positions can change.