Answer
The average velocity during the first 3 seconds is 80 meters per second.
Work Step by Step
Velocity=Distance/ Time
Time (3 seconds) is already given to us. We must use the given formula to find the distance traveled.---X= 50(3) + 10$(3)^{2}$
X=240 meters
Velocity=240 meters$\div$3 seconds
Velocity= 80 mps
