On a velocity vs. time graph what does a straight line with negative tell you

-- If a velocity/time graph is a straight line, that tells us that the acceleration is constant.

-- If the line has negative slope, then we know that the acceleration is negative.

. . . As long as the line is above the x-axis, the object is moving forward but slowing down.  

. . . When the line drops below the x-axis, the object is moving backward and speeding up.

(If you meant that the line has negative-something-else, then I don't know what to tell you about that part.)

can u provide the graph and if its not possible

then i can tell u the segment where the

average time interval starts degrading is the segment where the car is slowing down

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.