Find out the circumference of the roller first. Wheel circumference (i.e. circumference) =πd (generally we take the approximate value of π as 3. 14). The title has given us the length of the diameter, so we can bring in the numbers directly. Then the wheel circumference is: 3.14×1.5 = 4.71(m). The wheel rotates 8 times per minute. Now multiply the wheel circumference by 8, and you can calculate the length of the wheel pressing the road surface every minute: 4.7 1×8=37.68 (m).