<p>I have the answers but the book doesn’t supply a solution…</p>
<li><p>A cylinder has a volume of 0.2 m^3. It is composed of two different materials, with densities of 100 kg/m^3 and 300 kg/m^3 respectively. If each of these materials has an equal mass, what is the mass of the cylinder?
ANSWER: ** 30 kg</p></li>
<li><p>What is the mass of an abject that has a latent heat of fusion of 300 J/kg that begins at its melting point and is half melted after it absorbs 600 J of heat?
ANSWER: [C] 4 kg</p></li>
</ol>
<p>I would like to know how to arrive at these answers. Thanks.</p>
<ol>
<li>If the useful work done by a heat engine is equal to the amount of heat released by the engine, what is its efficiency?
ANSWER: [C] 50%</li>
</ol>
<ol>
<li><p>d = m / V, let d1 = 100 and d2 = 300. Then:
m1 = m2
d1<em>V1 = d2</em>V2
100<em>V1 = 300</em>V2
V1 = 3<em>V2
But we also have V1 + V2 = 0.2, so:
3</em>V2 + V2 = 0.2
V2 = 0.05
m2 = d2<em>V2 = 300</em>0.05 = 15 kg
mass = m1 + m2 = 30 kg</p></li>
<li><p>The object is half melted after 600 J, so it absorbed half of 300 J/kg = 150 J/kg. Then 600 J / (150 J/kg) = 4 kg.</p></li>
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<p>Thank you so much.</p>
<p>for 24 e = 1-Tc/Th which for idealized problems = 1-Qc/Qh and then Qc = 1/2 of Qh so its basically 1-1/2 = 1/2 and then times 100 for percent. T = the temp in kelvin and Q = the heat in any units.</p>