Final answer:
To find the pressure exerted by the square box, we calculate the area as 9 m² and use the formula P = F/A to find that the pressure is 9 N/m².
Step-by-step explanation:
The question is asking to calculate the pressure exerted by a square box with a force of 81N and a side length of 3 meters. Pressure is defined as the force applied perpendicular to the surface of an object per unit area over which that force is distributed. To find the pressure, we can use the formula P = F/A, where P is pressure, F is force, and A is area.
First, we calculate the area of the square box by squaring the length of one side: A = side · side = 3m · 3m = 9m². Now, we can calculate the pressure using the given force (81N) and the calculated area (9m²): P = 81N / 9m² = 9N/m².
Therefore, the answer is A. 9 N/m².