Understanding the Concepts

* Acceleration: Acceleration is the rate of change of velocity over time. In this case, the aircraft is accelerating at 3 meters per second squared (m/s²). This means its velocity increases by 3 meters per second every second.

* Initial Velocity: We're not given an initial velocity, so we'll assume the aircraft starts from rest (initial velocity = 0 m/s).

Formula

We can use the following formula to calculate the final velocity (v):

v = u + at

Where:

* v = final velocity

* u = initial velocity

* a = acceleration

* t = time

Calculation

1. Plug in the values:

v = 0 + (3 m/s²) * 4 s

2. Solve for v:

v = 12 m/s

Answer

The aircraft gains a velocity of 12 meters per second in 4 seconds.