I'm in middle school, but I think I know the answer, I am sorry if I am wrong.
It's D
Answer:
The time required for sucrose transportation through the tube is 8.4319 sec.
Explanation:
Given:
L = 0.025 m
A = 6.5×10^-4 m^2
D = 5×10^-10 m^2/s
ΔC = 5.2 x 10^-3 kg/m^3
m = 5.7×10^-13 kg
Solution:
t = m×L / D×A×ΔC
t = (5.7×10^-13) × (0.025) / (5×10^-10)×(6.5×10^-4)×(5.2 x 10^-3)
t = 8.4319 sec.
The first telescopes were refracting telescopes ... a tube
with lenses at both ends. The quality of the image depends
on the quality of both lenses, because the light must pass
through both of them.
The reflecting telescope was an improvement, because the
light doesn't have to go through the mirror. The quality of the
primary mirror only depends on the shape and shinyness of
its surface.
If you could carve an optically perfect parabolic surface out of
a piece of wood and coat it with a thin layer of shiny silver, then
you could use a log to make a good reflecting telescope.
II seem to recall that Newton made one out of brass !
There isn't really a center of the universe.
Geometrically the center would be the location out of which the universe started expanding but it is impossible to find such a point.
Theories about universal expansion are talking about space at any given point expanding at a rate equal to that of any other point according to Hubble's Law