- #1
VincentweZu
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Homework Statement
A Kennedy half-dollar has a mass that is 1.150 x 10-2 kg. The coin is a mixture of silver and copper, and in water weighs 0.1011 N. Determine the mass of silver in the coin.
Homework Equations
Explicit givens: m = 1.150 x 10-2kg
apparent weight = 0.1011N
Implicit givens: density of water = 1 x 103kg/m3
density of copper = 8890 kg/m3
density of silver = 10500 kg/m3
Fg = mg
FB = pwatergV
The Attempt at a Solution
Since the apparent weight is given (0.1011N). the actual weight should be defined using:
Fg = 0.1011 + FB (Buoyancy force)
Fg = 0.1011 + pwatergV
the mass of the coin should be the sum of the mass of silver and copper therefore:
m = msilver + mcopper
m = msilver + pcopperV
I isolated for V since it is an unknown variable in both equations
V = (m - msilver)/pcopper
After substituting V and I solved for msilver and got 9.77 x 10-4kg however the answer which is provided to me is 6.3 x 10-3kg
I don't understand what I did wrong for this question! I've triple checked my work, may someone please point out where I have made a mistake?