How would a speed vs. time line graph appear if an airplane moved at a
positive acceleration?

Explanation:

Acceleration is the time rate of change, or the rate, of the velocity. Therefore, the slope y/x of a speed vs time graph would give the acceleration. If the acceleration is said to be positive, the graph would be a straight line that is at a constant increase over time.

blue light is scattered in different directions by the tiny molecules of air. blue is scattered more than other colours because it has a shorter distance to travel which results in smaller waves. this is why we see a blue sky most of the time.