A 2.55 kg piece of lead at 40 degree Celsius is placed in a very large quantity of water at 10 degree Celsius and thermal equilibrium is eventually reached. Calculate the entropy change of the lead that occurs during this process. The specific heat of lead is 130 J/(kg K).

An air standard cycle with variable specific heats is executed in a closed system and is composed of the following four processes. 1-2 isentropic compression 100 kpa and 22°c to 600 kpa 2-3 v=constant heat addition to 1500 k 3-4 isentropic expansion to 100 kpa 4-1 p=constant heat rejection to initial state (a) show the cycle on p-v and t-s s (b) calculate the net work output per unit mass (409 kj/kg) (c) determine the thermal efficiency (47.9%)