TERMODINAMIKA
Departemen Fisika
Fakultas Matematika dan Ilmu Pengetahuan Alam
Institut Pertanian Bogor
Latihan
1. Satu mol gas ideal yang mula-mula ada pada
tekanan 1 atm dan suhu 0°C ditekan secara isotermis
dan kuasi statik sehingga tekanannya menjadi 2 atm.
Hitung
(a) volume gas mula-mula,
(b) usaha yang diperlukan untuk menekan gas
(c) panas yang dikeluarkan gas selama proses
kompresi tersebut.
2. Sebuah mesin kalor bekerja pada dua isobarik (105Pa
dan 3×105Pa) dan dua isokhorik (0,5 L dan 2 L).
(a) Gambarkan siklus mesin tersebut dalam diagram
p-V.
(b) Hitung kerja yang dihasilkan mesin tiap siklus.
3. Sebuah mesin Carnot bekerja pada suhu 400 K dan
900 K.
(a) tentukan efisiensi mesin. Jika kalor yang diserap
sistem pada tandon suhu tinggi adalah 5000 J tiap
siklusnya, tentukan
(b) kalor yang dibuang sistem pada tandon suhu
rendah
(c) kerja yang dilakukan sistem tiap siklus.
4. Satu mol gas ideal mula-mula mengalami ekspansi
bebas dari V1 = 12,3 L dan T1 = 300 K sampai V2 =
24,6 L dan T2 = 300 K. Gas ini kemudian dikompresi
secara isotermal dan kuasi statik kembali ke keadaan
semula.
(a) berapakah perubahan entropi semesta untuk satu
siklus yang lengkap?
(b) berapakah usaha yang terbuang dalam siklus ini?
5. An engine operates with 1 mol of an ideal gas, for
which Cv = 3/2R and Cp = 5/2R, as its working
substance. The cycle begins at P1 = 1 atm and V1 =
24.6 L. The gas is heated at constant volume to P2 =
2 atm. It then expands at constant pressure until
V2 = 49.2 L. During these two steps, heat is
absorbed by the gas. The gas is then cooled at
constant volume until its pressure is again 1 atm. It is
then compressed at constant pressure to its original
state. During the last two steps, heat is rejected by
the gas. All the steps are quasi-static and reversible.
(a) Show this cycle on a PV diagram. Find the work
done, the heat added, and the change in the
internal energy of the gas for each step of the cycle.
(b) Find the efficiency of the cycle.
6. One mole of an ideal monatomic gas at an initial
volume V1 = 25 L follows the cycle shown in
All the processes are quasistatic. Find
temperature of each state of the cycle,
heat flow for each part of the cycle, and
efficiency of the cycle
Figure.
(a) the
(b) the
(c) the
7. Two moles of a diatomic gas are carried through the
cycle ABCDA shown in the PV diagram in Figure. The
segment AB represents an isothermal expansion, the
segment BC an adiabatic expansion. The pressure and
temperature at A are 5 atm and 600 K. The volume at
B is twice that at A. The pressure at D is 1 atm. (a)
What is the pressure at B? (b) What is the
temperature at C? (c) Find the work done by the gas
in one cycle and the thermodynamic efficiency of this
cycle.