1. What is the true density of water?
The true density of water is 1 g/cm³. (Actually, the exact density if water is not really 1 g/cm³, but a bit less (very, very little less), at 0.9998395 g/mol at 40 degree Celsius)
2. What variables change the density of water?
Temperature and purity can change the density of water.
3. How does water go against the concept of "Thermal Expansion"?
When water is a liquid, the water molecules are packed relatively close together but can slide past each other and move around freely(as stated earlier, that makes it a liquid). As the temperature increases or decreases from 4 degree Celsius, the density of water decreases.
Answer:
We can define power as:
P = W/t
where W is work, and t is time.
And the work needed to climb a distance (we can assume that climb a set of stairs is equivalent to climbing a given height) is:
W = g*h*m
Where:
g = gravitational acceleration
h = height climbed
m = mass.
g and h are the same for Juan and his sister, and the only thing that changes is the mass
The work for Juan is:
Wj = g*h*M
And for his sister, that has half his
Wa = g*h*M/2.
Then the power for Juan, is:
Pj = Wj/t1 = (g*h*M)/t1
Where t1 is the time that Juan needs to climb the stairs.
And for Anna is:
Pa = Wa/t2 = (g*h*M/2)/t2
Where t2 is the time that Anna needs to climb the stairs:
We know that they have the same power, then:
Pj = Pa
(g*h*M)/t1 = (g*h*M/2)/t2
M/t1 = M/2*t2
t1 = 2*t2
This means that the time in which Juan climbs the stairs is twice the time that Anna needs to climb the stairs.
The pressure of a submerged object in a fluid is given by:
where ρ is the density of the fluis, g is the acceleration of gravity, h is the depth of the object and Patm is the pressure of the atmosphere. In this case we know that:
• The density of water is 1000 kg/m^3
,
• The acceleration of gravity is 9.8 m/s^2
,
• The depth of the object is 3 km, that is, 3000 m.
,
• The atmospheric pressure is 101325 pascals.
Plugging these values in the equation given above we have:
Therefore, the pressure at this depth is 2.95x10^7 Pa.