1)The speedometer on a car’s dashboard measure

Question

average speed
average velocity
instantaneous acceleration
instantaneous speed
2)A car moving on a straight road increases its speed from 30 m/s to 50 m/s in a distance of 180 m. If the acceleration is constant, how much time elapses for the auto to move this distance?  
9 s
3.6 s
6 s
4.5 s
3)

Answer 1

a = (50-30)/t = 20/t

180 = 30t + a/2 t^2
180 = 30t + 10t
t = 4.5

check:
30(9/2) +20/9 (9/2)^2 = 135 + 20/9*81/4 = 180