Answer:
21.75 m
Explanation:
t = Time taken for the car to slow down = 0.75 s
u = Initial velocity = 50 m/s
v = Final velocity = 8 m/s
s = Displacement
a = Acceleration
Equation of motion

Acceleration is -56 m/s²

The distance covered in the 0.75 seconds is 21.75 m
Average speed = (total distance covered) / (time to cover the distance)
Ian's total distance covered = (2km + 0.5km + 2.5km) = 5 km.
His time to cover the distance = 3 hours.
Average speed = (5 km) / (3 hrs)
Average speed = (5/3) (km/hr)
<em>Average speed = 1.67 km/hr</em>
The impact would be great it would possibly freeze the work or melt the polar ice caps and flood the world to were we would invent technology light years away.