Answer:
The answer is 1.87nm/s.
Explanation:
The 
water loss must be replaced by of sap. 110g of sap corresponds to a volume of
thus rate of sap replacement is
The volume of sap in the vessel of length 
is
,
where 
is the cross sectional area of the vessel.
For 2000 such vessels, the volume is
taking the derivative of both sides we get:
on the left-hand-side 
is the velocity 
of the sap, and on right-hand-side 
; therefore,
and since the cross-sectional area is
;
therefore,
solving for we get:
which is the upward speed of the sap in each vessel.
<h2>Answer: The astronauts are falling at the same rate as the space shuttle as it orbits around earth</h2>
The astronauts seem to float because they are in free fall just like the spacecraft.
However, although they are constantly falling on the Earth, they do not fall because the ship orbits at a sufficient speed (in the same direction of rotation of the Earth) so that the centrifugal force is balanced with the Earth's gravitational pull.
In other words:
The spaccraft and the astronauts are in free fall but the Earth's surface will never be reached as long as they does not decrease the speed.
Then, as they accelerate toward Earth (regardless of their mass), it curves beneath them and never comes close.
That's why astronauts, having the same acceleration as the spacecraft, feel weightless and see themselves floating.
Answer:
He is incorrect. Dissolving salt in water and evaporation of the water are both physical changes. The reappearance of salt is evidence that the change was reversible by a physical change, so it could not be a chemical change.
