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polet [3.4K]
3 years ago
7

Gold in its pure form is too soft to be used for most jewelry. Therefore, the gold is mixed with other metals to produce an allo

y. The composition of gold alloys are always calculated by mass, using the karat (kt) as a unit of measure. A karat represents a proportion by mass of one part in twenty-four. The higher the karat value, the higher the proportion of gold in relation to the total metal content. Pure gold is therefore 24 karat, while an 18-karat gold alloy contains (at least) 18 parts (by mass) of gold out of 24 parts total.
In a sample of 18-karat gold, 75 percent of the total mass is pure gold, while the rest is typically 16 percent silver and 9 percent copper. If the density of pure gold is rhogold = 19.3 g/cm^3, while the densitites of silver and copper are respectively rhosilver = 10.5 g/cm^3 and rhocopper = 8.90 g/cm^3.
a) What is the overall density rho18kt of this alloy of 18-karat gold?
Express your answer in grams per cubic centimeter to three significant figures.
Physics
1 answer:
Novay_Z [31]3 years ago
6 0

Answer:

Explanation:18kt alloy contains

i) 75% of gold

rhogold=19.3g/cm^3

=75/100×19.3

=14.475g/cm^3

ii) 16% of silver

rhosilver=10.5g/cm^3

=16/100×10.5

=1.68g/cm^3

iii) 9% of copper

rhocopper =8.90g/cm^3

=9/100×8.9

=0.801g/cm^3

Overall density of 18kt gold

=(0.801+1.68+14.475)g/cm^3

=16.956g/cm^3

=17g/cm^3 to 3s.f

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3 years ago
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A real object is 10.0 cm to the left of a thin, diverging lens having a focal length of magnitude 16.0 cm. What is the location
amm1812

Answer:

A)6.15 cm to the left of the lens

Explanation:

We can solve the problem by using the lens equation:

\frac{1}{q}=\frac{1}{f}-\frac{1}{p}

where

q is the distance of the image from the lens

f is the focal length

p is the distance of the object from the lens

In this problem, we have

f=-16.0 cm (the focal length is negative for a diverging lens)

p=10.0 cm is the distance of the object from the lens

Solvign the equation for q, we find

\frac{1}{q}=\frac{1}{-16.0 cm}-\frac{1}{10.0 cm}=-0.163 cm^{-1}

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Answer:

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Explanation:

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Thus: R = 1.7*m*g

Distance (s) = 2.3 m

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