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Use differentials to estimate the amount of metal in a closed cylindrical can that is 10 cm high and 4 cm in diameter if the metal in the top and the bottom is 0.3 cm thick and the metal in the sides is 0.05 cm thick.

Respuesta :

Answer:

The volume of metal in a can is 13.8 cm³.

Explanation:

Given that,

Height = 10 cm

Diameter = 4 cm

Thickness at bottom = 0.3 cm

Thickness at side = 0.05 cm

The change in radius = 0.05 cm

The total change in height is

[tex]dh=0.3+0.3 = 0.6\ cm[/tex]

The volume V of a cylinder in term of height and radius r

Using formula of volume

[tex]V(h,r)=\pi\times r^2\times h[/tex]

On differentiated with respect to r

[tex]\dfrac{dV}{dr}=2\pi r h[/tex]...(I)

On differentiated with respect to h

[tex]\dfrac{dV}{dh}=\pi r^2[/tex]

The total differentialis,

[tex]dV=\dfrac{dV}{dr}dr+\dfrac{dV}{dh}dh[/tex]

Put the value into the formula

[tex]dV=2\pi rh dr+\pi r^2 dh[/tex]

Put the value into the formula

[tex]dV=2\pi\times2\times10\times0.05+\pi\times(2)^2\times0.6[/tex]

[tex]dV=13.8\ cm^3[/tex]

Hence, The volume of metal in a can is 13.8 cm³.