The caravan has an initial speed of
85 km/h × (1000 m/km) × (1/3600 h/s) ≈ 23.611 m/s
If it slows down at a constant rate, then it will cover a distance x such that
0² - (23.611 m/s)² = 2 (-1.3 m/s²) x
Solve for x :
x = -(23.611 m/s)² / (2 (-1.3 m/s²)) ≈ 214.417 m ≈ 210 m
