A jetliner, traveling northward, is landing with a speed of 67 m/s. Once the jet touches down, it has 765 m of runway in which to reduce its speed to 5.1 m/s. Compute the average acceleration (magnitude and direction) of the plane during landing (take the positive direction to be northward).

Answer 1

(Vf)^2 = Vo^2 + 2a*d,
a = (Vf^2-Vo^2)/2d,
a=((5.1)^2-(67)^2) / 1530 = -2.92m/s^2.

Negative acceleration means that the plane is slowing down.