Two cylinders are made of the same material. Cylinder A is one-fourth (1/4) the length of cylinder B and it has a radius that is four times greater than the radius of cylinder B. What is the ratio of the mass of cylinder A to the mass of cylinder B?

Respuesta :

Answer:

[tex]M_{A}[/tex] : [tex]M_{B}[/tex]  = 4 : 1

Explanation:

Given that:

Volume of a cylinder = [tex]\pi[/tex][tex]r^{2}[/tex]h

For cylinder A, [tex]l_{A}[/tex] = [tex]h_{A}[/tex] = [tex]\frac{1}{4} l_{B}[/tex] and [tex]r_{A}[/tex] = 4[tex]r_{B}[/tex].

Volume of cylinder A = [tex]\pi[/tex][tex](4r_{B}) ^{2}[/tex] × [tex]\frac{1}{4} l_{B}[/tex]

                                   = 4[tex]\pi[/tex][tex]r_{B} ^{2}[/tex] [tex]l_{B}[/tex]

Volume of cylinder B =  [tex]\pi[/tex][tex](r_{B}) ^{2}[/tex] [tex]l_{B}[/tex]

                                  =  [tex]\pi[/tex][tex]r_{B} ^{2}[/tex][tex]l_{B}[/tex]

To determine the ratio of their masses, density (ρ) is defined as the ratio of the mass (M) of a substance to its volume (V).

i.e    ρ = [tex]\frac{M}{V}[/tex]

Thus, since the cylinders are made from the same material, they have the same density  (ρ). So that;

density of A = density of B

density of A = [tex]\frac{M_{A} }{4\pi r_{B} ^{2}l_{B} }[/tex]

density of B = [tex]\frac{M_{B} }{\pi r_{B} ^{2}l_{B} }[/tex]

⇒            [tex]\frac{M_{A} }{4\pi r_{B} ^{2}l_{B} }[/tex]  =  [tex]\frac{M_{B} }{\pi r_{B} ^{2}l_{B} }[/tex]

The ratio of mass of cylinder A to that of B is given as;

                       [tex]\frac{M_{A} }{M_{B} }[/tex]  =  [tex]\frac{4\pi r_{B} ^{2} l_{B} }{\pi r_{B} ^{2} l_{B} }[/tex]

⇒                        [tex]\frac{M_{A} }{M_{B} }[/tex] = [tex]\frac{4}{1}[/tex]

Therefore, [tex]M_{A}[/tex] : [tex]M_{B}[/tex]  = 4 : 1

Answer:

4.

Explanation:

Hello,

In this case, since we are talking about the same material, their densities are the same:

[tex]\rho _A=\rho _B[/tex]

And each density is defined by:

[tex]\rho _A=\frac{m_A}{V_A} \\\\\rho _B=\frac{m_B}{V_B}[/tex]

Thus, we also define the volume of a cylinder:

[tex]V_{cylinder}=\pi r^2h[/tex]

Therefore, we obtain:

[tex]\rho _A=\frac{m_A}{\pi r_A^2h_A}[/tex]

[tex]\rho _B=\frac{m_B}{ \pi r_B^2h_B}[/tex]

Now, the given information regarding the the length and the radius is written mathematically:

[tex]h_A=\frac{1}{4} h_B\\\\r_A=4 r_B[/tex]

So we introduce such additional equations in:

[tex]\frac{m_A}{\pi r_A^2h_A}=\frac{m_B}{\pi r_B^2h_B}\\\\\frac{m_A}{\pi (4r_B)^2(\frac{1}{4}h_B)}=\frac{m_B}{\pi r_B^2h_B}\\\\\frac{m_A}{m_B} =\frac{\pi (4r_B)^2(\frac{1}{4}h_B)}{\pi r_B^2h_B}[/tex]

So we simplify for the radius and lengths:

[tex]\frac{m_A}{m_B} =\frac{\pi (4r_B)^2(\frac{1}{4}h_B)}{\pi r_B^2h_B}\\\\\frac{m_A}{m_B} =16 *\frac{1}{4}\\ \\\frac{m_A}{m_B} =4[/tex]

So the ratio of the mass of cylinder A to the mass of cylinder B is 4.

Best regards.