Can anyone teach me what this question means?
For a fixed mass, the density of a particular sphere p kg/m^3, is inversely proportional to the cube of its radius, r m. When p=8kg/m^3, r=4m. Find its density when r=5m.
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It means you gotta find yourself an advanced physics teacher
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The question wants you to apply your algebra skills in the following: density = mass / volume,
volume of sphere V = (4*pi*r^3)/3, and the property of inverse relations saying the product of two variables are constanct.
In this case, density times the voume of sphere has to be equal to the mass whether the radius is 4m or 5m, since the mass is fixed according to the problem.
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What it means is, when the sphere gets large (increasing radius form 4m to 5m), its overall density will get smaller (because its a fixed mass)…
I’ll work out the problem in a sec…
Answer is 4.096…
Density=M/((4/3)*pi*r^3)
8 = M/((4/3)*pi*4^3)
M = 8 * ((4/3)*pi*4^3)
M = 2144.66
Density = 2144.66/((4/3)*pi*5^3)
Density = 4.096kg/m^3
And the person who posted below me has mental problems it would seem, if you increase the volume, something has to decrease–and that something is density for a fixed mass. They aren’t constants, obviously, if the volume is increasing.
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