Can anyone help me in question (b)

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.

e/c, where e is its total energy

distance = 150m

displ = root (50 ^2 + 100^2)

root(2500+10000)

root 125000