Question

The speed limit on suburban roads is 50 km/h. You are traveling at the limit when an empty bag blows onto the road from behind a parked car 5.0m in front of you. If you maintain your speed how long will it be before you hit?

Answer 1

50000 m/h / 3600 s/h = v m/s

time to impact = 5.0 m / v

Answer 2

5m / 50km/hr * 1km/1000m * 3600s/hr = 5*3600 / 50*1000 = 0.36s

or, since 50 km/hr = 50000m/3600s = 13.89 m/s
5m / 13.89m/s = 0.36s