106年 - 學士後西醫物理及化學106物理#77053

2.A layer of oil with density 800 kg/m ³ floats on top of a volume of water with density 1,000 kg/m ³ . A block floats at the oil-water interface with 1/4 of its volume in oil and 3/4 of its volume in water, as shown in the figure below. What is the density of the block ? (A) 200 kg/m³ (B) 850 kg/m³ (C) 950 kg/m³ (D) 1,050 kg/m³ (E) 1,800 kg/m³ 

3. X rays of wavelength λ= 0.250 nm are incident on the face of a crystal at angle θ, measured from the crystal surface. The smallest angle that yields an intense reflected beam is θ = 14.5°. Which of the following gives the value of the interplanar spacing d? ( sin 14.5° 1/4 )(A)0.125 nm (B) 0.250 nm (C) 0.500 nm (D) 0.625 nm (E) 0.750 nm

 4. A rod of length L and mass M is placed along the x-axis with one end at the origin, as shown in the figure below. The rod has linear mass density , where x is the distance from the origin. Which of the following gives the x-coordinate of the rod’s center of mass? (A) (B) (C) (D)(E)

 5. A long, straight, hollow cylindrical wire with an inner radius R and an outer radius 2R carries a uniform current density. Which of the following graphs best represents the magnitude of the magnetic field as a function of the distance from the center of the wire? (A) (B) (C) (D) (E)送分

8. A star radiates uniformly in all directions. At a distance of 5.0 ✖ 10¹² m from the star, the intensity of the radiation from the star is 15 W / m₂ . What is the total power output of the star? (A)   3.2✖10³⁸W (B) 4.7✖10 ²⁷W  (C)  3.8✖10²⁶ W(D)  7.5✖10¹³W  (E)   1.1✖10¹⁵W

13. A boy pulls a wooden box along a rough horizontal floor at constant speed by means of a force as shown. In the diagram f is the magnitude of the force of friction, N is the magnitude of the normal force, and Fg is the magnitude of the force of gravity. Which of the following must be true? (A) P = f and N = Fg (B) P = f and N ＞ Fg (C) P ＞ f and N ＜ Fg (D) P ＞ f and N = Fg (E) None of the above.

32. Which of the following graphs represents the magnitude of the electric field as a function of the distance from the center of a solid charged conducting sphere of radius R? (A) (B) (C) (D) (E)

35. The mass of α particle is 6.601✖10^-27 kg. If the α particle falls through the 100 kV potential difference, then the velocity of the α particle is: (e =1.602✖10^-19 C）(A)(B) (C) (D) (E)

36. What is the pressure on a swimmer 2 m below the surface of a swimming pool? (normal atmospheric pressure ) (A)(B) (C) (D) (E)

39. The electric potential in an xy plane is given byV . What is the magnitude of the electric field at the point (3.0 m, 2.0 m)? (A) 5.0 N /C (B) 6.0 N /C (C) 8.0 N /C (D) 10 N /C (E) 14 N /C

40. A cyclotron has a dee radius R and is operated at an oscillator frequency f in Hz. What is the magnitude of the magnetic field B needed for deuterons to be accelerated in the cyclotron? The mass of the deuteron is m in kilograms, f is in Hz, and B is in Tesla. (A) 2πmfR /q (B) 2πmf/ (Rq) (C) 2πmf /q (D) (E)

41. A 2.0 kg particle moves along an x axis, being pushed by a variable force directed along that axis. Its position is given by. What is the force on the particle at t = 2.0 s ? (A) (B) (C) (D) (E)

43. A particle with position vector . What is the torque on the particle about the origin? (A) (B) (C) (D) (E)

44. A disk with a rotational inertia of  5.0 k.gm² rotates around its central axis while undergoing a torque given by . The disk’s angular momentum is 2.5kg m ²/sat time t =1.0 s. What is the disk’s angular momentum at t = 2.0 s ? (A) (B) (C) (D) (E)

46. A sound wave from a sound generator radiates uniformly in all directions in  22.0 ℃air. The sound intensity level is 50 dB at a distance of 4.00 m from the sound generator. The frequency of the sound wave is 500 Hz. At what distance from the sound generator is the sound intensity level 30 dB? (A) 12.6 m (B) 40.0 m (C) 80.0 m (D) 6.67 m (E) 16.0 m

48. A cup of tea is made with 0.250 kg of C o 85.0 water. Then, the cup of tea cools down to room temperature  20.0℃ . What is the entropy change of the water while it cools? (For water,) (A) 200 J / K (B) 230 J / K (C) 1050ln(1.22) J / K (D) 1050ln(0.818) J / K (E) 190 J / K

49. A Carnot engine operates between two temperatures TH and TC. It takes in 600 J of heat from high-temperature reservoir at T_H = 327℃ in each cycle and gives up 200 J to the low-temperature (TC) reservoir. What is the thermal efficiency of the cycle? (A) 67% (B) 33% (C) 75% (D)50%(E)25%

51. The diagram shows a U-tube having cross-sectional area A and partially filled with oil of density . A solid cylinder, which fits the tube tightly but can slide without friction, is placed in the right arm. The system reaches equilibrium. The weight of the cylinder is: (A) ALρg (B) L ³ ρg (C) Aρ(L + h)g (D) Aρ(L – h)g (E) None of the above.

52. A solid brass ball of mass 0.280 g will roll smoothly along a loop-the-loop track when released from rest along the straight section. The circular loop has radius R = 14.0 cm, and the ball has radius r << R. What is h if the ball is on the verge of leaving the track when it reaches the top of the loop? (A) 47.8 cm (B) 27.8 cm (C) 57.8 cm (D) 37.8 cm (E) 78.3 cm

53. The emf E = 1.2 kV, C = 6.5 μF, R₁ = R₂ = R₃ = 0.73 MΩ. With C completely uncharged, switch S is suddenly closed (at t = 0). At t = 0, what is current i1 in resistor R₁? (A) 3.3✖10^-3 A (B) 3.3✖10^-4 A (C) 1.1✖10^-4 A (D) 1.1✖10^-3 A (E) 2.2✖10^-3 A

54. The following shows a rod of length L = 10.0 cm that is forced to move at constant speed v = 5.00 m/s along horizontal rails. The rod, rails, and connecting strip at the right form a conducting loop. The rod has resistance 0.400 Ω; the rest of the loop has negligible resistance. A current i = 100 A through the long straight wire at distance a = 10.0 mm from the loop sets up a (nonuniform) magnetic field through the loop. Find the emf. (μ0 = 4π10-7 T  m/A, ln 2 = 0.693, ln 10 = 2.303, ln 11 = 2.398) (A) 2.4✖10^-4 V (B) 5.8✖10^-3 V (C) 4.8✖10^-5 V (D) 3.9✖10^-4 V (E) 8.8✖10^-4 V

55. If the five lenses shown below are made of the same material, which lens has the shortest positive focal length? (A) (B) (C) (D) (E)

56. For quantum model, E = hν = hc / λ, where E is photon energy in unit of eV, h is the Planck’s constant ( ), ν is the frequency (s ^-1 ), λ is the wavelength in meters (m), then E✖λ (eV m) is: (A)  1.24 ✖10^{- 3} (B)  1.24✖ 10^{- 4} (C) 1.24 ✖10^-5 (D)  1.24✖ 10^{- 6} (E)  1.24✖ 10^-7

57. A particle with mass m and charge q, moving with a velocity v, enters a region of uniform magnetic field B, as shown in the figure below. The particle strikes the wall at a distance d from the entrance slit. If the particle’s velocity stays the same but its charge-to-mass ratio is doubled, at what distance from the entrance slit will the particle strike the wall? (A) 2d (B) (C) d (D) (E)

58. The position of a particle moving on x-axis is given by  x = , with x in meters and t in seconds. Which statement in the following is correct? (A) The particle is moving in the positive direction of x with a speed of 1.5m/s at t =1.0 s. (B) The acceleration of the particle at t = 1.0 s is -0.50 m / s ² . (C) The acceleration of the particle is constant. (D) The particle is moving in the negative direction of x with a speed of 0.50m/s at t =1.0 s. (E) The velocity of the particle is constant.

60. A rod of semiconducting material with length L and cross-sectional area A lies along the x-axis between x = 0 and x = L . Its resistivity varies with x according to . The material obeys Ohm’s Law. What is the total resistance of the rod? (A)(B)(C)(D) (E)