That's false. No medium = no sound.
Answer:
a = -4/5 m/s^2
Explanation:
Acceleration = change in velocity / time
change in velocity = final velocity - initial velocity
a = (20 m/s - 60 m/s) / 50 s
a = -40 m/s / 50 s
a = -4/5 m/s^2
hope this helps! <3
This number has 3 sig figs.