This preview shows page 1. Sign up to view the full content.
Unformatted text preview: rmal
equilibrium is established after a while as a result of heat transfer between the blocks and the lake water. Determine the total
entropy change for this process. FIGURE P7–62
IRON
50 kg LAKE 15°C COPPER
20 kg FIGURE P7–53 Entropy Change of Ideal Gases
7–54C Prove that the two relations for entropy change
of ideal gases under the constantspecificheat assumption
(Eqs. 7–33 and 7–34) are equivalent. 7–63 An insulated pistoncylinder device initially contains
300 L of air at 120 kPa and 17°C. Air is now heated for 15 min
by a 200W resistance heater placed inside the cylinder. The
pressure of air is maintained constant during this process. Determine the entropy change of air, assuming (a) constant specific heats and (b) variable specific heats.
7–64 A pistoncylinder device contains 1.2 kg of nitrogen gas
at 120 kPa and 27°C. The gas is now compressed slowly in a
polytropic process during which PV 1.3 constant. The process
ends when the volume is reduced by onehalf. Determine the
entropy change of nitrogen during this pro...
View
Full
Document
This document was uploaded on 11/28/2012.
 Spring '09

Click to edit the document details