Question

What will be the heat flow when two systems at different temperatures come in contact?

• A. ${20}^{\circ }C$ to a system at $307K$
• B. ${30}^{\circ }C$ to a system at $323K$
• C. ${50}^{\circ }C$ to a system at $303K$
• D. ${60}^{\circ }C$ to a system at $358K$
• E. ${70}^{\circ }C$ to a system at $370K$

Answer 1

The correct option is C ${50}^{\circ }C$ to a system at $303K$

When two objects having different temperature are brought together, energy will always be transferred from the hotter (the object at higher temperature) to the cooler (the object at lower temperature). The objects will exchange thermal energy, until thermal equilibrium is reached, i.e. until their temperatures are equal.

${20}^{o}C=273+20=293K\Rightarrow$ Heat flow will from the system at $307K$ to the system at ${20}^{o}C$

${30}^{o}C=303K\Rightarrow$ Heat flow will from the system at $323K$ to the system at ${30}^{o}C$

${50}^{o}C=323K\Rightarrow$ Heat flow will from the system at ${50}^{o}C$ to the system at $303K$

${60}^{o}C=333K\Rightarrow$ Heat flow will from the system at $358K$ to the system at ${60}^{o}C$

${70}^{o}C=343K\Rightarrow$ Heat flow will from the system at $370K$ to the system at ${70}^{o}C$