JEE Main & Advanced Physics Thermometry, Calorimetry & Thermal Expansion Question Bank Self Evaluation Test - Thermal Properties of Matter

  • question_answer
    A piece of metal weighs 45g in air and 25g in a liquid of density\[\text{1}\text{.5 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{3}}}\,\text{kg - }{{\text{m}}^{\text{-3}}}\]kept at\[3{{0}^{\operatorname{o}}}C\]. When the temperature of the liquid is raised to\[40{}^\circ C,\], the metal piece weighs 27g. The density of liquid at\[40{}^\circ C\], is\[1.25\times 1{{0}^{3}}kg -{{m}^{-3}}\]. The coefficient of linear expansion of metal is

    A) \[1.3\times {{10}^{-3}}/{}^\circ C\]

    B) \[5.2\times {{10}^{-3}}/{}^\circ C\]

    C) \[2.6\times {{10}^{-3}}/{}^\circ C\]

    D) \[0.26\times {{10}^{-3}}/{}^\circ C\]

    Correct Answer: C

    Solution :

    [c] \[{{V}_{1}}=\frac{4\left( 5-25 \right)g}{{{d}_{1}}}\]and \[{{V}_{2}}=\frac{\left( 45-27 \right)g}{{{d}_{2}}}\] \[\therefore \,\,\,\,\frac{{{V}_{1}}}{{{V}_{2}}}=\frac{20}{18}\times \frac{{{d}_{2}}}{{{d}_{1}}}\] or \[\frac{{{V}_{1}}}{{{V}_{1}}\left( 1+{{r}_{metal}}\times 10 \right)}=\frac{20}{18}\times \left[ \frac{{{d}_{1}}}{\left( 1+{{r}_{\ell }}\times 10 \right){{d}_{1}}} \right]\] After simplifying, we get \[\alpha =\frac{{{\gamma }_{metal}}}{{}}=2.6\times {{10}^{-3}}{{/}^{o}}C\]


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