Answer:
The relationship between the initial stored energy 
and the stored energy after the dielectric is inserted 
is:
c) 
Explanation:
A parallel plate capacitor with 
that is connected to a voltage source 
holds a charge of 
. Then we disconnect the voltage source and keep the charge 
constant . If we insert a dielectric of 
between the plates while we keep the charge constant, we found that the potential decreases as:
The capacitance is modified as:
The stored energy without the dielectric is
The stored energy after the dielectric is inserted is:
If we replace in the above equation the values of V and C we get that
Finally
-- There is nothing on the list of choices that you provided that has no mass.
-- There are no "things" that have no mass. Every sample of a liquid, a gas,
or a solid has mass, even if it's only an atom or two.
I think the only possible items you could name that have no mass would be
spiritual, conceptual, or sensory ones, like maybe ...
-- idea
-- conviction
-- belief
-- concept
-- image
-- sound
-- illusion
-- impression
-- agreement
-- inclination
-- tendency
-- sparkle
-- tingle
-- pain
Things like that.
An estimated value for gravity at a distance r from the middle of the Earth can be gotten by supposing that the Earth's density is spherically symmetric. The gravity hinge on only on the mass inside the sphere of radius r. All the assistances from outside cancel out as a fall out of the inverse-square law of gravitation. Another result is that the gravity is the same as if all the mass were concentrated at the midpoint. Therefore, the gravitational acceleration at this radius is
g(r) = GM(r) / r²
M(r) = mass enclosed by radius r.
If the Earth had a continual density ρ, the mass would be M(r) = (4/3)πρr³ and the dependence of gravity on distance would be
g(r) = (4/3)πGρr
G = 6.674e-11 m³/kgs²
The mechanical advantage is (4meters) / (0.8meter) = <em><u>5</u></em> .
