54. An observer on the Earth measures the speed of spacecraft A to be 0.50c and the speed of spacecraft B to be -0.40c. What is the velocity of spacecraft B as observed by the crew on spacecraft A? (Here c is the
speed of light. The Lorentz velocity transformation is )

(A) -c/6
(B) -3c/5
(C) -2c/5
(D) -c/4
(E) -3c/4

50. Suppose that 1 mole of an ideal gas undergoes a free expansion to three times its initial volume.What is the change of entropy? (The universal gas constant is R.)(A) 2R ln 2 (B) R ln 2 (C) R ln 3 (D) R ln 4 (E) 2R ln 4

51. A proton of mass m and charge q is in uniform circular motion perpendicular to a magnetic fieldB . The radius of the circle is r. What is the speed of the proton?(A) qBr/3m (B) 2qBr2/(2m(r + 1)) (C) qBr2/(2m(r + 1))(D) qBr/2m (E) qBr/m

52. During each heartbeat, approximately 70 cm3 of blood is pushed from the heart at the mean arterial pressure of 100 mmHg. By assuming 72 beats per minute, what is the amount of external power output of the heart?(A) less than 0.20 W (B) 0.50 W (C) 0.84 W(D) 1.1 W (E) larger than 5.0 W

53. A square 10-turn coil with edge-length 50 cm carries a current of 2 A. ft lies in the xy plane with magnetic moment in the z direction. ft is placed in a uniform magnetic field (T). What is the magnetic potential energy of the coil in the magnetic field?(A) -2 Joule (B) -1.5 Joule (C) 1.5 Joule (D) 2 Joule (E) 2.4 Joule

55. Two sources of light illuminate a double slit simultaneously. One has wavelength 570 nm and the second has an unknown wavelength. The fifth bright fringe (m=5) of the unknown wavelength overlaps the forth bright fringe (m=4) of the light of 570 nm wavelength. What is the unknown wavelength?(A) 326 nm (B) 380 nm (C) 456 nm (D) 512 nm (E) 713 nm

56. A family member is ready to have a brain scan using technetium-99*, an excited isotope with 6.0-hour half-life. The hospital makes this short-lived Tc-99* from the decay of molybdenum-99 then delivers it to the nuclear medicine department. After production of Tc-99*, the hospital staff takes 90 minutes to transport it to the operating room. What is an appropriate amount of Tc-99* to be produced by the technician-in-charge for the medical requirement of 10 mg of Tc-99*?(A) 10 mg (B) 12 mg (C) 16 mg (D) 20 mg (E) 24 mg

57. Light of wavelength 400 nm falls on a metal surface having a work function 1.70 eV. What is the maximum kinetic energy of the photoelectrons emitted from the metal?(A) 1.41 eV (B) 1.70 eV (C) 2.82 eV (D) 3.11 eV (E) 4.51 eV

58. You wish to pick an element for a photocell that will operate via the photoelectric effect withvisible light. Which of the following is suitable? (hc/e=1.2398× eV⋅m, the wavelength ofvisible light: 380 ~ 750 nm)(A) Silver (4.26 eV) (B) Copper (4.5 eV) (C) Aluminum (4.06 eV)(D) Magnesium (3.66 eV) (E) Sodium (2.36 eV)

59. X-rays are produced by bombarding a tungsten target with high-energy electrons. The K-shell electron is ejected, and then an L-shell electron jumps to the K-shell and releases an X-ray photon.The binding energies of shell and orbital are listed in the table. Estimate the energy of this X-ray photon.(A) 10 keV (B) 12 keV (C) 58 keV (D) 69 keV (E) 81 keV

60. A beam of light with intensity 40 W/m2 is polarized along the y-axis asshown. This beam passes through a polarizing filter with a polarizationdirection that makes an angle θ=60° with the y-axis. What is the intensity ofthe light transmitted through the filter?(A) 5 W/m2 (B) 10 W/m2 (C) 20 W/m2 (D) 30 W/m2 (E) 35 W/m2