Final answer:
The action Chris took when tilting the concrete buggy with handles extending beyond the wheels is described as 'overturning'. This represents the concrete buggy being tipped past its normal upright balance, indicating a loss of stability.
Step-by-step explanation:
When Chris tips a concrete buggy so far that the handles extend beyond the wheels on either side, the action Chris took with the concrete buggy is termed as overturned. This description indicates that the buggy has tipped over its normal upright position, which corresponds to the action of overturning rather than merely maneuvering, balancing, or positioning.
In the context of physical actions and stability, overturning implies that the center of mass has moved beyond the base of support, causing the buggy to tip over.