Answer:
Gravity is the centripetal force when the moon orbits the earth.
Since the direction of the force and the direction of the path is perpendicular, the person is not doing any physical work.
That's a weird graph, but judging from the units the acceleration is the slope of the graph.
a = (0.8 - 0.3)/(0.16 - 0.055) = 4.76 m/s²
