Final answer:
Acceleration requires a specified time interval for its calculation, and without it, we cannot definitively determine the acceleration of the air caused by the fan.
Step-by-step explanation:
The acceleration of the air as a result of the fan's action involves a change in velocity. To determine this, we need to consider that the velocity of the air changes from 0 m/s (at rest) to 3 m/s (speed given). The density of the air plays a role in determining the mass flow rate, which we can then use to calculate the force exerted by the fan on the air (considering the efficiency of 10%), and then the acceleration using Newton's second law (F = ma).
However, more information or a specific time interval is required to calculate the acceleration from the given initial and final velocities. Since acceleration is defined as the change in velocity (Δv) over time (Δt), without a given time interval, we cannot accurately determine the acceleration of the air.