Calculating Rate of Change for Sphere Volume and Surface Area

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SUMMARY

The discussion focuses on calculating the rate of change of a sphere's volume and surface area using the formulas V = 4/3 * π * r³ for volume and A = 4 * π * r² for surface area. Participants clarify that to find the rate of change dV/dA, one must apply the chain rule, resulting in the formula dV/dA = (dV/dr) / (dA/dr). The derivatives are determined as dV/dr = 4 * π * r² and dA/dr = 8 * π * r, leading to the final result of dV/dA = r/2.

PREREQUISITES
  • Understanding of calculus, specifically derivatives and the chain rule.
  • Familiarity with the formulas for the volume and surface area of a sphere.
  • Basic knowledge of mathematical notation and operations.
  • Ability to manipulate algebraic expressions.
NEXT STEPS
  • Study the application of the chain rule in calculus.
  • Explore the geometric properties of spheres and their derivatives.
  • Learn about related rates in calculus problems.
  • Investigate practical applications of volume and surface area calculations in physics.
USEFUL FOR

Students studying calculus, mathematics educators, and anyone interested in understanding the relationship between geometric properties and their rates of change.

freman1075
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hi everyone,
i am having trouble with this rate of change question.
I need to find the rate of change of a sphere with a volume of V= 4/3*pi*r^3 in respect to it's surface area of A= 4*pi*r^2
can anyone give me a hand?
Thanks
 
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Since the surface area- the derivative of the volume-is A=4*pi*r^2, it would seem that change there would be the derivative, 8*pi*r.
 
freman1075 said:
hi everyone,
i am having trouble with this rate of change question.
I need to find the rate of change of a sphere with a volume of V= 4/3*pi*r^3 in respect to it's surface area of A= 4*pi*r^2
can anyone give me a hand?
Thanks

So you want to find dV/dA? Use the chain rule dV/dr= (dV/dA)(dA/dr) so dV/dA= (dV/dr)/(dA/dr). Find dV/dr and dA/dr and divide.
 
HallsofIvy said:
So you want to find dV/dA? Use the chain rule dV/dr= (dV/dA)(dA/dr) so dV/dA= (dV/dr)/(dA/dr). Find dV/dr and dA/dr and divide.

so if dV/dr = 4*pi*r^2
and if dA/dr = 8*pi*r

i just divide the two?
 
freman1075 said:
hi everyone,
i am having trouble with this rate of change question.
I need to find the rate of change of a sphere with a volume of V= 4/3*pi*r^3 in respect to it's surface area of A= 4*pi*r^2
can anyone give me a hand?
Thanks

dv/dr = 4/3*pi*3*r^2 = 4*pi*r^2

da/dr = 4*pi*2*r = 8*pi*r

dv/da = dv/dr * dr/da = r/2
 
HallsofIvy said:
So you want to find dV/dA? Use the chain rule dV/dr= (dV/dA)(dA/dr) so dV/dA= (dV/dr)/(dA/dr). Find dV/dr and dA/dr and divide.

freman1075 said:
so if dV/dr = 4*pi*r^2
and if dA/dr = 8*pi*r

i just divide the two?
Well, that is what I said in the post you quoted!

Lizzie, when a person asks for help, please do not just do the problem for them!
 
ok sorry hallsofivy
 
to find the rate of change for designing of catalytic oxidation converter
SO2+0.5O2 <---->SO3
 

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