#1. A metal block with heat capacity C and temperture T h is thrown into the oce
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Question
#1. A metal block with heat capacity C and temperture Th is thrown into the ocean. (a) Find the minimum entropy change of the universe delta Suniverse. (b) Show it's postive.
#2 You are pumping up your bicycle tire. The pump feels hot. Why? Please explain this question in thermodynamic.
#3 Consider two coins. The first is a "fair coin", P1 head = 1/2 , P1 tail = 1/2. The other coin is "unfair", P2 h = 3/4, P2 t = 1/4. (a) What is the probability of flipping and obtaining no head and one tail. (b). What is the Gibbs entropy of the unfair systm? Compart with a fair pair.
#4 One mole of a monatomic ideal gas (C=3/2) is contained in a volume with a sliding piston and adbatic walls. The sysmtem is mechanical equilibrium with outside pressure P = Po . A quantity of heat Q is added to system. Find Pf , Tf , Vf , delta U, delta S, delta H.
Please, try to explain in detail. I have the answers but I dont know how they come up with the answers. Thanks in advance.
Explanation / Answer
2. When a gas is compressed (Suppose that the piston moves inward, so that the atoms are slowly compressed into a smaller space) rapidly, temperature increases because temperature and volume of gas are inversely proportional to each other according to gas laws. As far as the Ideal Gas Law is concerned any gas will tend to heat up as it is compressed and cool down when it expands. When the compression is released, the temperature drops.
When you use the bicycle pump, you are compressing the air as you're pumping it into the tire so the pump is exposed to that increase in temperature. So over time, this increased temperature causes the pump to become hotter. The temperature of tyre would be lower than because compression is getting released. The air doesn't get decompressed in the pump, so no cooling effect in pump.
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