Final answer:
The combined weight of the spade trail arm and blade needs to be supported by a minimum of two personnel.
Step-by-step explanation:
In this question, the subject being referred to is the weight of the spade trail arm and blade. This question is related to Physics since weight is a concept in Physics that involves the force of gravity acting on an object. Weight is the force exerted by a body due to its mass and the acceleration due to gravity. In this case, the combined weight of the spade trail arm and blade needs to be supported by a minimum of two personnel.