Question

Approximate the change in the volume of a sphere when its radius changes from r = 30 ft to r=10.1 ft [v(r)=4/3πr^3]. When r changes from 10 ft to 10.1 ft, ΔV=_________

Answer 1

Answer: ∆V for r = 10.1 to 10ft

∆V = 40πft^3 = 125.7ft^3

Approximate the change in the volume of a sphere When r changes from 10 ft to 10.1 ft, ΔV=_________

[v(r)=4/3Ï€r^3].

Explanation:

Volume of a sphere is given by;

V = 4/3πr^3

Where r is the radius.

Change in Volume with respect to change in radius of a sphere is given by;

dV/dr = 4πr^2

V'(r) = 4πr^2

V'(10) = 400π

V'(10.1) - V'(10) ~= 0.1(400π) = 40π

Therefore change in Volume from r = 10 to 10.1 is

= 40πft^3

Of by direct substitution

∆V = 4/3π(R^3 - r^3)

Where R = 10.1ft and r = 10ft

∆V = 4/3π(10.1^3 - 10^3)

∆V = 40.4π ~= 40πft^3

And for R = 30ft to r = 10.1ft

∆V = 4/3π(30^3 - 10.1^3)

∆V = 34626.3πft^3