A tiny feather and a huge sledgeham- mer are dropped on the surface of the earth's
moon, at the same time, from the same height,
they will hit the moon's surface simultane
ously.

diagram is missing, but i will try to explain your doubt.

answer:

amplitude is the maximum displacement or distance moved on a point of a vibrating body or wave measured from its equilibrium position.it is equal to half the length of vibration path.

explanation:

newton's third law, for every action there is an equal and opposite reaction.

luster is not a good characteristic to use by itself because luster is the property of minerals that indicates how much the surface of a mineral reflects light. the luster of a mineral is affected by the brilliance of the light used to observe the mineral surface.

i think the answer would be reserve.