Acceleration is defined as the rate of change of velocity, which, simply put, is a mouthful to describe how fast something speeds up, slows down, or turns. The equation for acceleration is
a = Δv / Δt,
or your final velocity - your starting velocity, then divided by the amount of time. It can also be expressed as
a = (Vf - Vi) / t,
Where Vf is your final velocity, Vi is your initial velocity, and t is the time traveled.
The question gives us that the helicopter moves from a starting velocity of 30 m/s to a final velocity of 40 m/s in the span of 5 seconds. This means we can fill in the variables to the equation, where
Vf = 40,
Vi = 30, and
t = 5.
Plug these known variables into the original equation, and we get
a = (Vf - Vi) / t = (40 - 30) / 5.
From here, the answer comes down to 10 / 5, or 2 m/s^2.
Hope this helps! If you have any questions, don't hesitate to ask :D
