Physics
posted by Greg .
If an airplane is moving at a constant velocity of 400 m/s for 20 s, what is its acceleration during this period?
0 m/s squared
20 m/s squared
40.82 m/s squared
need more information
wouldnt it be need more information because isnt acceleration ending velocity minus starting velocity divided by the time, or can it be 20 m/s squared where 400 was over 20 s

You have the right idea. Yes, the AVERAGE acceleration is just as you stated, (ending velocity  starting velocity)/time. The problem says the starting and ending velocities are the same (always 400m/s). (400m/s  400m/s) is 0. So the acceleration during this time is 0.