42. A balloon filled with air is pulled into a tank of water at room temperature. As the balloon sinks, the air pressure inside the balloon ______.
(A) increases
(B) remains the same
(C) decreases
(D) increases then decreases
(E) decreases then increases

38. A ball of mass m is released from a height of ?. What is its speed when it is at a height of y? (Gravitational acceleration is g) (A) (B) (C)(D) (E)

39. A wheel of radius ? and moment of inertia I is mounted on a frictionless horizontal axle as shown in the figure. A light cord wrapped around the wheel supports an object of mass m. What is the linear acceleration of the object? (Gravitational acceleration is g) (A) (B) (C) (D) (E)

40. A block with a speaker bolted to it is connected to a spring having spring constant k = 20 N m as shown in figure. The total mass of the block and speaker is 5 kg, and the amplitude of this unit’s motion is 0.5 m. The speaker emits sound waves of frequency 440 Hz. Determine the highest frequency heard by the person to the right of the speaker. (Assume that the speed of sound is 343ms) (A) 481 Hz (B) 471 Hz (C) 461 Hz (D) 451 Hz (E) 441 Hz

41. A wire of length L, Young’s modulus ?, and cross-sectional area A is stretched elastically by an amount ∆L . It behaves as a spring by using the Hooke’s law. What is the work done in stretching the wire by an amount ∆L? (A)(B)(C)(D)(E)

43. Ethanol of density ?? flows smoothly through a horizontal pipe that tapers in cross-sectional area from A1 to A2 (A1 = 2A2) as shown in the figure. The pressure difference between the wide and narrow sections of pipe is ∆P. What is the volume flow rate of the ethanol? (A) (B) (C) (D) (E)

44. An ideal monoatomic gas of one mole is at pressure P, volume V, and temperature T. The gas is heated at constant volume to 2T. Then the gas is allowed to expand at constant temperature to 2V. Finally, the gas cools at constant pressure to T. What is the net entropy change for this ideal gas? (The ideal gas constant is R) (A) R ln 2 (B) −R ln 2 (C) 0 (D) R ln 4 (E) not calculatable by the above information

45. The figure shows a closed cycle for a gas. From c to b, 60 J is transferred from the gas as heat. From b to a, 100 J is transferred from the gas as heat, and the magnitude of the work done by the gas is 80 J. From a to c, 400 J is transferred to the gas as heat. What is the work done by the gas from a to c? (A) -240 J (B) 240 J (C) 320 J (D) -320J (E) -160 J

46. A quantity of an ideal gas is compressed to half its initial volume. The process may be adiabatic, isothermal or occurring at isobaric. Rank those three processes in order of the work required of an external agent, least to greatest. (A) adiabatic, isothermal, isobaric (B) adiabatic, isobaric, isothermal (C) isothermal, adiabatic, isobaric (D) isobaric, adiabatic, isothermal (E) isobaric, isothermal, adiabatic

47. An ideal parallel-plate capacitor connected to a battery of voltage V0, it has charge of magnitude Q0 on its plates. The plates are pulled apart to a separation from d to 2d while the capacitor remains connected to the battery. After the plates are 2d apart, what are the magnitude of the charge on the plates and the potential difference between them? (A) 0.5Q0, 0.5V0 (B) 0.5Q0, V0 (C) Q0, V0 (D) 2Q0, V0 (E) 2Q0, 2V0

48. A group of identical capacitors is connected first in series and then in parallel. The combined capacitance in parallel is 100 times larger than for the series connection. How many capacitors are in the group? (A) 5 (B) 10 (C) 50 (D) 100 (E) 200