We are assuming the wheel is tangent to the ground. Unrealistic, but let's go with it.

The y coordinate is given by ...[1]

The wheel rotates rad/sec.

When the wheel is 9 feet off the ground, then it has swept out an angle of

From [1], differentiating, we get

We know the angular velocity is and

Entering in the values, we get

Another way is:

Entering in the 47.71 seconds to get to 9 feet, we get:

0.157 ft/sec. as before.