Answer:
the free-fall acceleration on the moon is 1.68 m/s^2
Explanation:
recall the formula for the gravitational potential energy (under acceleration of gravity "g"):
PE = m * g * h
replacing with our values for the problem:
46 J = 91 * g * 0.3
solve for the "g" on the Moon:
g = 46 / (91 * 0.3)
g = 1.68 m/s^2