Answer:
Position A/Position E
, 
Position B/Position D
,
, for 
Position C
, 
Explanation:
Let suppose that ball-Earth system represents a conservative system. By Principle of Energy Conservation, total energy (
) is the sum of gravitational potential energy (
) and translational kinetic energy (
), all measured in joules. In addition, gravitational potential energy is directly proportional to height (
) and translational kinetic energy is directly proportional to the square of velocity.
Besides, gravitational potential energy is increased at the expense of translational kinetric energy. Then, relative amounts at each position are described below:
Position A/Position E
, 
Position B/Position D
,
, for 
Position C
, 
Answer:
(A) because there are the same number of atoms of each element shown on both sides
Explanation:
The Law of conservation of mass says that in a reaction the matter of the products should be equivalent to the matter of the reactants and the mass of the system should remain constant over time.
In a chemical reaction, while atoms bond is breaking of 1 substance than new bonds are formed in another substance and new substances are formed. However, in the overall reaction, they keep the same elements, no new elements can go and come from the outside. For example:
HCl + NaOH -----> NaCl + H2O
In this reaction, on both sides the same number of atoms of each element are present.
Velocity is defined as Distance divided by Time.
In other words, V = D/T.
Now that we have our formula, we can solve.
Let's plug in the numbers we have.
We have 12m [East (direction not necessary when solving yet)] for our distance, and 0.15s as our time.
Divide the distance (12 /) by the time (0.15)
12 / 0.15 = 80.
Your velocity is 80 m/s [E]
I hope this helps!