- #1
Sum Guy
- 21
- 1
Hello all.
I have a quick question about entropy... I've just been formally introduced to it.
Consider the example of a metal block of mass m and heat capacity Cp at temperature T1 = 60C being dropped into a large lake of temperature T2 = 10C.
$$\Delta S_{block} = \int\frac{dQ_{reversible}}{T} = \int_{T_1}^{T_2}\frac{C_pdT}{T}$$
I have a few questions... how would the block reaching thermal equilibrium with the lake be classed as a reversible process (it must be otherwise we wouldn't have the above calculation)? Why can we ignore the blocks mass? Are there any general tips you could provide that might help me tackle questions on entropy?
Many thanks.
I have a quick question about entropy... I've just been formally introduced to it.
Consider the example of a metal block of mass m and heat capacity Cp at temperature T1 = 60C being dropped into a large lake of temperature T2 = 10C.
$$\Delta S_{block} = \int\frac{dQ_{reversible}}{T} = \int_{T_1}^{T_2}\frac{C_pdT}{T}$$
I have a few questions... how would the block reaching thermal equilibrium with the lake be classed as a reversible process (it must be otherwise we wouldn't have the above calculation)? Why can we ignore the blocks mass? Are there any general tips you could provide that might help me tackle questions on entropy?
Many thanks.