A rotating beacon is located 7 miles out in the water. Let A be the point on the shore that is closest to the beacon. As the beacon rotates at 8 rev/min, the beam of light sweeps down the shore once each time it revolves. Assume that the shore is straight. How fast is the point where the beam hits the shore moving along the shore at an instant when the beam is lighting up a point 7 miles along the shore from the point A?

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