Physics, 06.05.2020 04:40, dejabrewer01
A mass m of a material is heated reversibly from temperature T1 to T2 at a constant pressure of P. In this problem, we are going to determine an expression for the change in entropy, ΔS. Assume we can heat the given material infinitesimally slowly so that the process is reversible. Therefore, heat in any infinitesimal step is given by the following:
dQ = mc_p dT,
where c_p is the specific heat. In general, the heat capacity of a material can be temperature-dependent. A general temperature-dependent empirical form for the specific heat for ideal gases and incompressible liquids such as water is as follows:
c_p(T) = A + BT + CT² + DT⁻²,
where A, B, C, and D are substance-dependent constants that can be determined empirically.
(a) Write an expression for the change in entropy ΔS for the system assuming the empirically temperature-dependent form of the specific heat.
(b) Calculate the change in entropy ın call for a sample of water with mass rn = 2.2 kg and changing temperature from T1 = 21.4°C to T2 = (21.4+10)°C The specific heat c of water is 1,000 cal /kg/K.
Answers: 3
Physics, 22.06.2019 22:50, mdg5605
The illuminance of a surface varies inversely with the square of its distance from the light source. if the illuminance of a surface is 120 lumens per square meter when its distance from a certain light source is 6 meters, by how many meters should the distance of the surface from the source be increased to reduce its illuminance to 30 lumens per square meter?
Answers: 3
Physics, 23.06.2019 01:30, antoniocapetillo80
Sally turns on her cellular telephone to speak to her friend who is located thousands of miles away. which of the following best describes how such a telephone is able to transmit and receive information? a. the cellular telephone transmits, receives, and encodes information using only sound waves. b. the cellular telephone transmits, receives, and encodes information using only electromagnetic waves. c. the cellular telephone transmits information by electromagnetic waves to a receiver which then encodes them and produces sound. d. the cellular telephone transmits information by sound waves to a receiver which then encodes them and produces electromagnetic waves.
Answers: 2
A mass m of a material is heated reversibly from temperature T1 to T2 at a constant pressure of P. I...
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