The odometer of a car reads 2000 km at the start of a trip and 2400 km at the end of the trip. If the trip took 8 h, calculate the average speed of the car in km h–1 and m s–1 .

Solution:
Distance covered by the car,
s = 2400 km – 2000 km = 400 km
Time elapsed, t = 8 h
Average speed of the car is, v_av = s / t =400 km / 8 h = 50 km h^–1

= 50 x 1000 m / 3600 s = 13.9 m s^–1
The average speed of the car is 50 km h^–1 or 13.9 m s^–1.