Final answer:
The physics question asks about the mechanical advantage of pushing a box up an inclined plane and the percentage of the required effort relative to the box's weight. The answer is approximately 67%, illustrating how the incline reduces the necessary effort.
Step-by-step explanation:
The subject of the question at hand is Physics, dealing specifically with the concepts of forces, incline planes, and the mechanics of motion. In physics, when an object is pushed up an inclined plane, the effort force applied to move the object is generally less than the gravitational force (weight) acting on the object. This situation demonstrates the mechanical advantage provided by the incline.
For the question about the box that weighs 210 N and requires 140 N to push it up an inclined 2.0 m length, we are asked to determine the percentage of effort to weight. The answer is 140 N / 210 N = 2/3 or approximately 67%, giving us the answer D. This calculation shows the efficiency of the inclined plane in reducing the effort needed to elevate an object.