ANSWER
Step-by-step explanation
We want to find the acceleration due to gravity on the moon.
To do this, we have to apply one of the equations of motion for a body falling freely under gravity:
where u = initial velocity
v = final velocity
g = acceleration due to gravity
t = time taken
Neil Armstrong dropped the hammer, so its initial velocity is 0 m/s:
We have to solve for g:
That is the acceleration due to gravity on the moon.