|Acceleration| = (change in speed) / (time for the change)
Change in speed = (50m/s - 20m/s) = 30 m/s
Time for the change = 5.0 sec
|Acceleration| = (30 m/s) / (5 sec) = 6 m/s² .
I wrote 'Acceleration' with absolute value lines ( | | ) around it,
because acceleration is actually a vector . . . it should have a
direction as part of its description. But we don't know anything
about its direction, so we can only talk about its magnitude (size).