Air enclosed in a sphere has density ρ = 1.4\

rabbitz42z8

rabbitz42z8

Answered question

2021-11-14

Air enclosed in a sphere has density ρ=1.4 kgm3. What will the density be if the radius of the sphere is halved, compressing the air within?

Answer & Explanation

pendukke

pendukke

Beginner2021-11-15Added 9 answers

Given data:
Density of air enclosed in a sphere is, ρ=1.4 kgm3.
Let m be the mass of the enclosed air and V=43πr2 be the volume of the sphere. Here, r is the radius of sphere. Then density is,
ρ=mV
Modified volume (V') is,
V=43π×(r2)3V=18×43πr2
V=18×V
Then new density is,
ρ=mV
ρ=mV8
ρ=8ρ
ρ=8×1.4=11.2 kgm3
Thus, the density if the radius of the sphere is halved is 11.2 kgm3.

fudzisako

fudzisako

Skilled2023-06-19Added 105 answers

Result:
2·ρ
Solution:
ρ=mV
For a sphere, the volume is given by the formula V=43πr3, where r is the radius.
Given that the initial density is ρ=1.4kgm3, we can substitute the initial values into the density equation to find the mass:
1.4=m43πr3
To find the new density when the radius is halved, we can substitute r2 for r in the equation above:
ρ=m43π(r2)3
Simplifying the equation, we get:
ρ=m43π(r2)3=8m43πr3=2·ρ
Therefore, the density will be doubled when the radius of the sphere is halved, compressing the air within.
xleb123

xleb123

Skilled2023-06-19Added 181 answers

Since we are dealing with a fixed amount of air enclosed in a sphere, the number of moles of gas (n) remains constant. Therefore, we can rewrite the ideal gas law as PV=constant.
The density of a gas is defined as ρ=mV, where m is the mass of the gas and V is the volume. In this case, the mass of the gas remains constant, so we can write ρ1=mV1, where ρ1 is the initial density and V1 is the initial volume.
When the radius of the sphere is halved, the volume of the sphere is reduced by a factor of 8 (since the volume of a sphere is proportional to the cube of its radius). Therefore, the new volume V2 is 18 times the initial volume V1.
Now, let's find the new density ρ2 when the air is compressed within the sphere.
We can write ρ2=mV2.
From the ideal gas law, we know that PV=constant.
Since the pressure P and the number of moles of gas n remain constant, we can write P1V1=P2V2, where P1 and P2 are the initial and final pressures, respectively.
Dividing both sides of the equation by V2 gives us P1=P2(V1V2).
Substituting the expression for V2, we have P1=P2(V118V1)=P2×8V1.
Since PV=constant, we can write ρ1P1=ρ2P2.
Substituting the expressions for ρ1 and P1 and rearranging the equation, we get ρ2=ρ1V18V1.
Simplifying the equation further, we find ρ2=ρ18.
Therefore, the density of the air will be ρ18 when the radius of the sphere is halved, compressing the air within.
Andre BalkonE

Andre BalkonE

Skilled2023-06-19Added 110 answers

We know that the volume of a sphere is given by the formula:
V=43πr3
Let's consider the initial volume, V1, and the final volume, V2, after halving the radius:
V1=43πr3
V2=43π(r2)3
Simplifying the equation for V2:
V2=43π·r38
V2=16πr3
Now, we can calculate the final density, ρ2, by using the formula:
ρ2=massvolume
The mass of the air enclosed in both cases remains the same, so we can write:
ρ1·V1=ρ2·V2
Substituting the values for V1 and V2:
ρ1·43πr3=ρ2·16πr3
Canceling out the common terms:
43ρ1=16ρ2
To find ρ2, we can rearrange the equation:
ρ2=43·61ρ1
ρ2=8ρ1
Therefore, the density of the air enclosed will be 8 times the initial density when the radius of the sphere is halved.

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