I feel retarded but I need help with a density problem.?

Question

Okay, so, if a mint decides to replace it's pure silver coin with a sandwich coin that is 1/2 silver and 1/2 copper and the volume of the coin (both the old style and the new) is O.24cm cubed, what is the difference in grams between the old coin and the new one?

Btw, the density of silver is 10.5 g/cm cubed and the density of copper is 9.0 g/cm cubed.

I'm just not sure how to get the density of an object made of two different elements and subsequently get the mass from knowing the density and the given volume.

I just need help understand how to work this problem, I don't need an answer.

Thanks

Answer 1

Grams in original coin:
(0.24 cm^3) * (10.5 g/cm^3) = 2.52 g

Grams in new coin:
(1/2)(0.24 cm^3)(10.5 g/cm^3) + (1/2)(0.24 cm^3)(9 g/cm^3)
= 1.26 g + 1.08 g
= 2.34 g

Answer 2

Density = mass / volume

mass = density x volume

Mass (Silver) = 10.5 g/cm x 0.24 cm
mass (Silver) = 2.52 g

If the silver and copper are in the proportions 1/2 : 1/2 then it is reasonable to assume the density to be the mean of the two given densities;-

(10.5 + 9.0)/2 = 9.75 g/cm^3

mass(Alloy) = 9.75 g/cm^3 x 0.24 cm^3
mass(Alloy) = 2.34 g

Answer 3

Mass = density * volume
Mass of sandwiched coin = 1/2 *total volume *( density of silver) + 1/2 * total volume * (density of copper)

Answer 4

mass (m) = density x volume
For the old one, m1 = 10.5*0.24
For the new one, m2 = (10.5 + 9)*0.12
m1 - m2 = 0.18 g
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Mental math approach:
Since half of the new coin has the same composition as the old one, the difference is caused by the other half. Therefore, the difference = 0.12(10.5-9) = 0.18 g.

Answer 5

density = mass/volume

All Silver coin

10.5 g/cm³ = m/0.24 cm³
m = 2.52 g of silver coin

1/2 silver 1/2 copper

Silver mass
10.5 g/cm³ = m/0.12 cm³
m = 1.26 g of silver

Copper mass
9.0 g/cm³ = m/0.12 cm³
m = 1.08 g of copper

Total mass of 1/2 silver 1/2 copper coin =
1.26 + 1.08 = 2.34 g

Difference = 2.52 - 2.34 = 0.18 g

Answer 6

Um, he took my answer