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A casting made of cast iron weighs 4.7 kg. The riser and gating system add another 2.5 kg to the total metal poured during the operation. The melting temperature of this grade of cast iron = 1180°C, its density = 7.6 g/cm3, specific heat = 0.46 J/g°C, and heat of fusion = 126 J/g. Assume that the specific heat has the same value for solid and molten metal. Compute (a) the unit energy for melting and pouring and (b) the total energy to heat the metal to a pouring temperature of 1300°C from a starting temperature of 25°C. (c) What is the volume of the casting?

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boffeemadrid

Answer:

712.5 J/g

5130000 J

618.421052632 cm³

Explanation:

[tex]c_p[/tex] = Specific heat = 0.46 J/g°C

[tex]\Delta T[/tex] = Change in temperature = (1300-25)°C

[tex]\Delta H_f[/tex] = Heat of fusion = 126 J/g

[tex]\rho[/tex] = Density = [tex]7.6\ g/cm^3[/tex]

Unit energy for melting and pouring is given by

[tex]Q=\Delta H_f+c_p\Delta T\\\Rightarrow Q=126+0.46(1300-25)\\\Rightarrow Q=712.5\ J/g[/tex]

The unit energy for melting and pouring is 712.5 J/g

Total energy is given by

[tex]E=mc_p\Delta T+m\Delta H_f\\\Rightarrow E=7.2\times 10^3\times 0.46(1300-25)+7.2\times 10^3\times 126\\\Rightarrow E=5130000\ J[/tex]

The total energy of the process is 5130000 J

Volume is given by

[tex]V=\dfrac{m}{\rho}\\\Rightarrow V=\dfrac{4700}{7.6}\\\Rightarrow V=618.421052632\ cm^3[/tex]

The volume of the casting is 618.421052632 cm³

Answer:

see file

Explanation:

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