Final answer:
The white plank will be 2 feet high from the ground after the water wheel rolls forward through an angle of pi/3 radians.
Step-by-step explanation:
To find the height of the white plank after the motion, we need to calculate the vertical displacement of the plank. Since the radius of the water wheel is 4 feet and the bottom of the wheel is 1 foot from the ground, the initial height of the white plank is 5 feet. The angle through which the wheel rolls is pi/3 radians.
The vertical displacement of the plank can be calculated using the formula: displacement = radius * (1 - cos(angle))
Substituting the values, we get: displacement = 4 * (1 - cos(pi/3))
Simplifying further, displacement = 4 * (1 - 0.5) = 2 feet.
Therefore, the white plank will be 2 feet high from the ground after this rolling motion.