8. If n moles of an ideal gas are expanded isothermally from an initial volume V₁ to a final volume V₂, the change in entropy is
(A) nRT In (V₂/V₁),
(B) nR In (V₂ /V₁),
(C) nk_B In (V₂/V₁),
(D) n Cp ∫dT/T,
(E) n Cp/T.

4. Water is flowing at 4.0 m/s in a circular pipe. If the diameter of the pipe decreases to 1/3 its former value, what is the velocity of the water downstream? (A) 1.0 m/s, (B) 2.0 m/s, (C) 8.0 m/s, (D) 16 m/s, (E) 36.0 m/s.

5. In which process will the internal energy of the system change? (A) An adiabatic compression of an ideal gas. (B) An isothermal expansion of an ideal gas. (C) An isobaric compression of an ideal gas. (D) A free expansion of an ideal gas. (E) Statements (a) and (c) are found to be correct.

6. An ideal heat engine can have an efficiency of 100% if the temperature of the low temperature reservoir is (A) 0°F. (B) 0℃. (C) 10 K. (D) 0K. (E) the same as the temperature of the heat source.

7. The reason that we can calculate the change in entropy of a system is that, (A) entropy always increases. (B) entropy always decreases. (C) systems always follow irreversible paths. (D) it depends only on the properties of the initial and final equilibrium states. (E) systems always follow reversible paths.

9. A body oscillates with simple harmonic motion along the x axis. Its displacement varies with time according to the equation x = 5.0 sin (πt + π/3). The velocity (in m/s) of the body at t = 2.0 s is (A)+8.0, (B) -8.0, (C) -5.0, (D) -14.0, (E) +14.0.

10. Calculate the average power needed to spin a uniform, solid disk of mass 2.2 kg and radius 0.70 m from rest to 10.0 rad/s in 2.3 s.(A)9.2W,(B)11.6 W, (C) 14.0 W, (D) 12.0 W, (E) 16.4 W.

11. Two long, parallel wires, separate by 10 cm. One carries a current of 5.0 A and another carries a current of 10,0 A in the opposite direction. Which of the following statements is true?(A) In region 1, the magnetic field is into the page and is never zero. (B) In region 2, the field is into the page and is never zero. (C) In region 3, the magnetic field is into the page and is never zero. (D) In region 3, the magnetic field is out of the page and can be zero. (E) There are no points where the field is zero.

12. A loop of wire locates at the upper side of a long wire carrying currents of 5A. When the loop falls down toward the wire at the speed ofy, what is the direction of force exerted on the loop by the long wire at this moment?(A) upward, (B) downward, (C) left, (D) right, (E) impossible to determine.

13. A Wi-Fi signal uses 5GHz frequency band for electromagnetic sinusoidal wave transmission. When the amplitude of electrical field of the EM wave is 6 V/m, what is the wave function of magnetic field B(x,t)? (u0 = 4π✖ 10-7 N/A2,ε0 = 8,85✖ 10-12F/m). (A) 5 X 107 cos(16.67x-3.14✖1010t).(B)5 X 107 cos(104.72x-3.14✖1010t). (C)2X10-8cos(16.67x-3.14✖1010t).(D)2X10-8co(104.72x-3.14X1010t). (E)0.17cos(16.67x-3.14X1010t).

14. A plane electromagnetic (EM) sinusoidal wave propagates in the x direction. Suppose the wavelength is 500.0 nm and the electrical field has an amplitude of 300.0 V/m. What is the intensity (average of poyting vector) of this EM wave (uo = 4π X 10-7N/A2,ε0= 8.85x10-12 F/m) (A)477.5 J/s.m2, (B) 337.6 J/s.m2, (C) 238.7 J/s.m2 , (D) 168.8 J/s.m2, (E) 119.4 J/s.m2.