A rectangular bar in a rectangular hole represents which type of pair?

• A. Completely constrained motion
• B. Partially constrained motion
• C. Incompletely constrained motion
• D. Freely constrained motion

Answer: (A)

The correct answer indicates that a rectangular bar in a rectangular hole represents a completely constrained motion. This means that the bar can only move in a specific manner determined by the constraints of the hole's dimensions.

In this scenario, the rectangular bar fits perfectly within the rectangular hole, allowing it to translate along the length of the hole but not to rotate or move in any other direction. The constraints ensure that the bar's movement is limited solely to the motion allowed by the dimensions of the hole—preventing any additional degrees of freedom that would enable rotation or lateral movement.

This type of pair is crucial in mechanical design and analysis where precise motion control is required, ensuring that components behave predictably under applied forces. By understanding this concept, it's easier to apply it in real-world mechanical systems where constraint types significantly impact functionality and performance.