A) 
The total energy of the system is equal to the maximum elastic potential energy, that is achieved when the displacement is equal to the amplitude (x=A):
(1)
where k is the spring constant.
The total energy, which is conserved, at any other point of the motion is the sum of elastic potential energy and kinetic energy:
(2)
where x is the displacement, m the mass, and v the speed.
We want to know the displacement x at which the elastic potential energy is 1/3 of the kinetic energy:
Using (2) we can rewrite this as
And using (1), we find
Substituting 
into the last equation, we find the value of x:
B) 
In this case, the kinetic energy is 1/10 of the total energy:
Since we have
we can write
And so we find:
Answer:
Density relates a mass to its volume.
Density varies with temperature
Density determines if a substance floats or sinks.
Density may have units of grams per milliliter (g/mL)
Explanation:
Density 
is a characteristic property of a substance or material and is defined as the relationship between the mass 
of a body or substance and the volume 
it occupies:
This means the density is inversely proportional to the volume.
On the other hand, density is a scalar quantity and according to the International System of Units its unit is 
, although it can be also expressed in 
.
It should be noted that the density of a body is related to its buoyancy, a substance or body will float on another fluid if its density is lower. In addition, if the pressure of the substance remains constant, as the temperature increases, the density decreases; this means density varies with the temperature as well.
Assuming the accleration applied was constant, we have
Then the force applied to the ball is given by
The answer is cardiovascular.
