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The mass of 4.5 cm3 of iron and 8 cm3 of copper is equal to 101.5g. The mass of 3 cm3 of iron is 6.8g greater than the mass of 2 cm3 of copper. Find the density of iron and the density of copper

Respuesta :

Nirina7
The answer 
m is the density of iron, and M is the copper's. so m=M=101.5g
the mass of 3 cm3 of iron is 6.8g ≥ the mass of 2 cm3 of copper.
first, we know the formula
m= d x v, where m is the mass, d is the density and v is the volume;
the density of the iron is d= m /v (from the formula m= d x v). It is d= 6.8/3=2.26 g/cm3. It was assumed that m≥M=d x 2, so 6.8≥2xd, it implies 
d is less than 3.4, (d≤6.8/2=3.4)
so the density of the copper is d ≤ 3.4 
isyllus

Answer:

The density of iron is 7.8 g/cm³ and density of copper is 8.3g/cm³

Step-by-step explanation:

The mass of 4.5 cm³ of iron and 8 cm³ of copper is equal to 101.5g.

The mass of 3 cm³of iron is 6.8g greater than the mass of 2 cm³ of copper.

Let the density of iron be x g/cm³ and density of copper be y g/cm³

Mass = Volume x Density

For sentence: "The mass of 4.5 cm³ of iron and 8 cm³ of copper is equal to 101.5"

[tex]4.5x+8y=101.5----------(1)[/tex]

For sentence: "The mass of 3 cm³of iron is 6.8g greater than the mass of 2 cm³ of copper"

[tex]3x=2y+6.8-------------(2)[/tex]

Now we will solve for x and y using elimination method.

[tex]4.5x+8y=101.5]\times 1[/tex]

[tex]3x-2y=6.8]\times 4[/tex]

[tex]4.5x+8y=101.5[/tex]

[tex]12x-8y=27.2[/tex]

Add both equation and eliminate y

[tex]16.5x=128.7[/tex]

[tex]x=7.8[/tex]

Put x=7.8 into equation 1

[tex]4.5(7.8)+8y=101.5[/tex]

[tex]8y=66.4[/tex]

[tex]y=8.3[/tex]

Hence, The density of iron is 7.8 g/cm³ and density of copper is 8.3g/cm³

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