Lets see who can answer this. Consider two identical iron spheres, one of which lies on a thermally insulation plate,whilst the other hangs from an insulation thread. Equal amounts of heat are given to the two spheres.Which will have the higher temperature. tip:think little deep.
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As a result of thermal expansion, the size of both the spheres increases. The centre of mass of the sphere lying on the plate rises,whilst that of the sphere hanging on the thread sinks.Thus the potential energy of the first sphere increases,whilst that of the second one decreases.|dw:1327904679861:dw| according to the first law of thermodynamics,the heat transferred to the spheres produces not only an increase in internal energy and the small amount of work done in expanding against the atmospheric pressure(which is same for both spheres),but also a change in gravitational potential energy.the pot energy of first sphere increases a little,therefore its internal energy increases by less than the residual heat transferred.Conversely,the decrease in pot energy of the hanging sphere contributed positively to the increase in its internal energy. In summary,the temperature of the sphere suspended will be higher.
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