1. Grandpa takes a walk to keep fit. He walked three kilometers in two hours. How many kilometers does he walk per hour on average? three
1.5 km. Speed = distance ÷ time, so Grandpa walks 1.5km every hour. The relationship between distance, speed and time is speed = distance/time. In science, speed is used to indicate the speed at which an object moves. Speed is numerically equal to the distance traveled per unit time. Calculation formula of speed: v = s/t.