Gravitational potential energy -> Kinetic energy -> Mechanical energy -> Electrical energy.
The water starts up (potential) and flows down (kinetic), the flowing water turns a big wheel (mechanical) which creates electricity (electrical).
The answer to this question would be: vitamin D
The UV is needed by the skin to make previtamin D3. Previtamin D3 or cholecalciferol made from the skin will be changed in the liver into 25- hydroxyvitamin D3 and then sent to the kidney to be changed into 1,25- dihydroxyvitamin D3. The last change in the kidney will active the vitamin D. Vitamin D has a role in the calcium absorption which was will strengthen the bone tissue.
Answer:
lipids are insoluble in water which is why lipids are often found in biological membranes and other waterproof coverings.
Answer:
The same as the escape velocity of asteorid A (50m/s)
Explanation:
The escape velocity is described as follows:

where
is the universal gravitational constant,
is the mass of the asteroid and
is the radius
and since the scape velocity is 50m/s:

Now, if the astroid B has twice mass and twice the radius, we have that tha mass is: 
and the radius is: 
inserting these values into the formula for escape velocity:

and we have found that
, so the two asteroids have the same escape velocity.
We found that the expression for escape velocity remains the same as for asteroid A, this because both quantities (radius and mass) doubled, so it does not affect the equation.
The answer is
Asteroid B would have an escape velocity the same as the escape velocity of asteroid A