Bonjour,
1) 240 tr/min = (240 : 60) tr/s = 4 tr/s
2) 120 km/h = (120 : 60) km/min = 2 km/min
3) 150 m/min = (150 × 10^(-3) × 60) km/h = 9 km/h
4) 5 m/s = (5 × 10^(-3) × 60 × 60) km/h = 18 km/h
5) 3 km/h = (3 × 10³ : 60) m/min = 50 m/min
6) 45 km/h = (45 × 10³ : 60 : 60) m/s = 12,5 m/s
Bonne journée !
