The composition of pennies has changed over the years, depending on a number of factors, including the availability of various metals. A penny minted in 1825 was pure copper; a penny minted in 1860 was 88% copper and 12% nickel; a penny minted in 1965 was 95% copper and 5% zinc; and a penny minted today is 97.5% zinc and 2.5% copper. Given that the densities of copper, nickel, and zinc are 8.92 g/cm^3 , 8.91 g/cm^3 , and 7.14 g/cm^3 , respectively, determine the density of each penny.

Respuesta :

Answer:

At 1825

   The value is   [tex]\rho_p =  8.9188 \ g/cm^3 [/tex]

At 1965  

   The value  is  

   The value is  [tex]\rho_p =  8.831 \ g/cm^3 [/tex]

At Today

The value is [tex]\rho_p = 8.8755 \ g/cm^3 [/tex]

Explanation:

From the question we are told that

The percentage of copper in 1825 penny is 100%

The percentage of copper in 1860 penny is 88%

The percentage of nickel is 1860 penny is 12%

The percentage of copper in 1965 penny is 95%

The percentage of zinc in 1965 penny is 5%

The percentage of copper in today's penny is 97.5%

The percentage of zinc in today's penny is 2.5%

The density of copper is [tex]\rho_c = 8.92 g/cm^3[/tex]

The density of zinc is [tex]\rho_z = 7.14 g/cm^3[/tex]

The density of nickel is [tex]\rho_n = 8.91 g/cm^3[/tex]

Considering 1825

The density of penny is [tex]\rho_p = 8.92 g/cm^3[/tex] because the penny was made up of 100% copper

Considering 1860

Generally the density of penny is mathematically evaluated as

[tex]\rho_p = [\frac{88}{100} * \rho_c] +[\frac{12}{100} * \rho_z][/tex]

=>  [tex]\rho_p  =  [\frac{88}{100} *  8.92 ] +[\frac{12}{100} * 8.91 ][/tex]

=>  [tex]\rho_p =  8.9188 \ g/cm^3 [/tex]

Considering 1965

Generally the density of penny is mathematically evaluated as

[tex]\rho_p = [\frac{95}{100} * \rho_c] +[\frac{5}{100} * \rho_n][/tex]

=>  [tex]\rho_p  =  [\frac{95}{100} *  8.92 ] +[\frac{5}{100} * 7.14 ][/tex]

=>  [tex]\rho_p =  8.831 \ g/cm^3 [/tex]

Considering today

Generally the density of penny is mathematically evaluated as

[tex]\rho_p = [\frac{97.5}{100} * \rho_c] +[\frac{2.5}{100} * \rho_z][/tex]

=>  [tex]\rho_p  =  [\frac{97.5}{100} *  8.92 ] +[\frac{2.5}{100} * 7.14 ][/tex]

=>  [tex]\rho_p =  8.8755 \ g/cm^3 [/tex]