A wheel with radius 1 m is rolled in a straight line through one complete revolution on a flat horizontal surface. How many meters did the center of the wheel travel horizontally from its starting location?
We can think of it like this :
We have a bike with tires that have a radius of one meter......when the bike moves such that its wheels travel through one revolution.....the linear distance traveled is just the circumference of the tire = 2 * pi * (1 meter) ≈ 6.28 meters
But......all the parts of the bike will travel the same distance....so....the center of the wheel also travels ≈ 6.28 meters......