91esa04 - 高雄㊩㈻大㈻㈨㈩㆒㈻年度㈻士後㊩㈻系招生考試試題 科目:普通物理 考試時間 80 分鐘 共 4 頁第 1 頁

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Unformatted text preview: 高雄㊩㈻大㈻㈨㈩㆒㈻年度㈻士後㊩㈻系招生考試試題 科目:普通物理㈻ 考試時間: 80 分鐘 共 4 頁第 1 頁 說明:㆒.選擇題用 2B 鉛筆在「答案卡」㆖作答,修正時應以橡皮擦拭,切勿使 用修正液(帶),未遵照正確作答方法而致無法判讀者,考生㉂行負責。 ㆓.試題應隨同試卷繳回,不得攜出試場。 壹、選擇題 (單選題,每題答對得 4 分,答錯倒扣 1 分,未作答者,不給分亦不扣分) 1. A 300N weight, 5m long rigid uniform ladder is leaning against a smooth vertical wall. A 750N weight man stands on a rung 4m up along the ladder from its base as shown in fig.1. What is the minimum coefficient of the statical friction between the ladder and the floor required to keep the system in equilibrium? The angle is 53.1° on a horizontal beam. ( cos53.1° = 0.6, sin53.1° = 0.8 ) (A) 0.22 (B) 0.42 (C) 0.46 (D) 0.54 Fig 1 (E) 1.90 2. An imaginary closed surface S of radius R is centered on the origin. A positive charge is originally at the origin, and the flux through the surface is Φe. The positive charge is slowly moved from the origin to a point R/2 away from the origin. Now the flux is . (A) 4Φe (B) 2Φe (C) Φe (D) Φe/2 (E) Φe/4 3. An incompressible fluid flows through a horizontal pipe. At one point in the pipe the pressure in the fluid is p1 and the fluid speed is v1. Further down the pipe pressure is p2 and the fluid speed is 2v1. What can be concluded about p1and p2? (A) p1 = p2 (B) p1 = 2p2 (C) p1 = 3p2 (D) p1 = 4p2 (E) only that p1>p2 4. A diffraction grating just resolves the wavelengths 400.0 nm and 400.1 nm in the first order. The number of slits in the grating is . (A) 400 (B) 1000 (C) 2500 (D) 3000 (E) 4000 5. A clear sheet of polaroid is placed on top of a simmilar sheet so that their polarizing axes make an angle of 30° with each other. The ratio of the intensity of emerging light to incident unpolarized light is . 3 1 ( cos30° = , sin30° = ) 2 2 (A) 1/4 (B) 1/3 (C) 1/2 (D) 3/4 (E) 3/8 6. What is the intensity ratio of sound for the heavy truck at 1.5m(90dB) to normal conversation at 1m(60dB)? (A) 1.5 (B) 103 (C) 0.67 (D) 1030 (E) 110-3 【背面㈲試題】 共 4頁 第2頁 7. What is the ratio of the shortest wavelength of the Balmer series to the shortest wavelength of the Lyman series in the spectrum of the Hydrogen atom? (A) 2 (B) 5 (C) 3 (D) 4 (E) 9 8. Some sunglasses are coated on one side with a thin film of MgF2 to reduce reflection from the glass surface. The index of refraction of MgF2 is 1.38; that of the glass is 1.50. What is the least coating thickness that eliminates (via interference) the reflections in the range of the visible spectrum (λ= 550 nm)? Assume that the light is approximately perpendicular to the glass surface. (A) 40 nm (B) 60 nm (C) 80 nm (D) 100 nm (E) 120 nm 9. The two headlights of a car are 1.4 m apart. At what maximum distance will the eyes resolve them? Assume that the pupil diameter is 5.0 mm, and use a wavelength of 550 nm for the light. (Consider only diffraction effects.) (A) 3 km (B) 5 km (C) 10 km (D) 15 km (E) 20 km 10. A flute (which we treat as a pipe open at both ends) is 60 cm long. How far from the mouthpiece should a hole be uncovered for the fundamental frequency to be 330 Hz? (The speed of sound is 330 m/s). (A) 35 cm (B) 40 cm (C) 45 cm (D) 50 cm (E) 55 cm 11. An ideal monatomic gas undergoes a quasistatic expansion to one-third of its initial pressure. Find the ratio of the final volume to the initial volume if the process is adiabatic.( γ = Cp/Cv = 5/3 for ideal monatomic gas, log3 = 0.5 ) (A) 10-0.1 (B) 100.3 (C) 100.5 (D) 100.6 (E) 100.7 12. A block with mass m = 250 g is fastened to a spring with spring constant k = 85 N/m. The system is excited to oscillate. Assume that there is a velocity-dependent damping force Fd = -bv in the system with b = 70 g/s. How long does it take for the amplitude of the damped oscillation to drop to half its initial value? ( ln2 = 0.693 ) (A) 3 s (B) 4 s (C) 5 s (D) 6 s (E) 7 s 13. A thin rod whose length L is 10 cm and whose mass m is 100 g, suspended at its midpoint from a long wire. Its period Ta of angular SHM (Simple Harmonic Motion) is measured to be 2.50 s. An irregularly shaped object is then hung from the same wire and its period Tb is found to be 5.0 s. What is the rotational inertia of the irregular object 1 mL2) about its suspension axis? (The rotational inertia for a rod is 12 (A) 1.73 ×10-4 kgm2 (B) 3.30 ×10-4 kgm2 (C) 4.62 ×10-4 kgm2 (D) 6.12 ×10-4 kgm2 (E) 7.64 ×10-4 kgm2 共 4頁 第3頁 14. In high-speed motion through air, the resisting force is approximately F = cv2. For a human body falling through air in a spread-eagle position, c is about 0.25 kg/m. An 80 kg sky diver jumps out of an airplane and reaches terminal speed before opening the parachute. What is the terminal speed? (A) 49 m/s (B) 56 m/s (C) 72 m/s (D) 84 m/s (E) 98 m/s 15. A neutral water molecule (H2O) in its vapor state has an electric dipole moment of magnitude 6.2 x10-30 Cm. How far apart are the molecule's center of positive and negative charge? (A) 1.9 pm (B) 2.9 pm (C) 3.9 pm (D) 4.9 pm (E) 5.9 pm 16. In a mass spectrometer, the initially stationary ion is accelerated by the electric field due to a potential V. The ion enters a separator chamber in which a uniform magnetic field B is perpendicular to the path of the ion. The magnetic field causes the ion to move in a semicircle, striking a photographic plate at distance x from the entry slit. Suppose that B = 80 mT and V = 1000 Volts, and ion of charge q = +1.60 ×10-19 C strikes the plate at x = 1.63 m, what is the mass of the ion? (A) 185.7 u (B) 204.9 u (C) 224.6 u (D) 241.5 u (E) 267.8 u 17. Consider a parallel-plate capacitor of plate area A and plate separation d. A potential difference Vo is applied between the plates. The battery is then disconnected, and a dielectric slab of thickness b and dielectric constant k is placed between the plates. Assuming A = 100 cm2, d = 1.00 cm, Vo = 90 V, b = 0.8 cm, k = 2.00. What is the capacitance with the slab in place? ( 0 = 8.85×10-12 C2/Nm2 ) (A) 14.8 pF (B) 16.8 pF (C) 17.9 pF (D) 20.9 pF (E) 21.9 pF 18. A 200g top spinning at 20 rev/s makes an angle of 30 to the vertical and precesses at a rate of 1 rev per 10.0 s. If its CM (Center of Mass) is 4.0 cm from its tip along its symmetry axis, what is the moment of inertia of the top? (A) 1.00 × 10-3 kgm2 (B) 2.04 × 10-3 kgm2 (C) 3.06 × 10-3 kgm2 (D) 4.08 × 10-3 kgm2 (E) 6.62 × 10-3 kgm2 19. A phone cord is 4.00 m long. The cord has a mass of 0.200 kg. If a transverse wave pulse travels from the receiver to the phone box in 0.100 s, what is the tension in the cord ? (A) 50.0 N (B) 60.0 N (C) 70.0 N (D) 80.0 N (E) 90.0 N 20. A thermodynamic system undergoes a process in which its internal energy decreases by 500 J. If at the same time, 220 J of work is done on the system, what is the thermal energy transferred to or from it? (A) 280 J (B) –280 J (C) 720 J (D) –720 J (E) 1220 J 【背面㈲試題】 共 4頁 第4頁 21. A dipole for which p 3.8 10 30 Cm is in a uniform field E 7 10 4 N/C. What is the external work needed to rotate the dipole from alignment with the field to an angle 60 to the field? ( cos 60° = 0.5; sin 60° = 0.9 ) (A) 1.33 × 10-25 J (B) 2.39 × 10-25 J (C) 3.99 × 10-25 J (D) 5.56 × 10-25 J (E) 7.12 × 10-26 J 22. A 5A current flows in a circular loop of radius 2 cm. The axis of the loop is at 30 to a uniform field 0.06 T. What is the magnitude of the torque on the loop? (A) 1.22 × 10-3 Nm (B) 1.88 × 10-3 Nm (C) 1.22 × 10-4 Nm (D) 1.88 × 10-4 Nm (E) 3.76 × 10-4 Nm 23. A 15 pF parallel-plate capacitor is connected to a 50 V battery. The area of each plate is 80 cm 2 . What is the energy density in the field? ( 0 = 8.85×10-12 C2/Nm2 ). (A) 2.62 × 10-4 J/m3 (B) 3.38 × 10-4 J/m3 (C) 5.00 × 10-4 J/m3 (D) 6.76 × 10-4 J/m3 (E) 7.97 × 10-4 J/m3 24. What minimum frequency of light is needed to eject electrons from a metal whose work function is 4.3 10 19 J ? ( h = 6.63×10-34Js ) (A) 1.9 × 1014 Hz (B) 3.8 × 1014 Hz (C) 4.6 × 1014 Hz (D) 5.2 × 1014 Hz (E) 6.5 × 1014 Hz 25. Through how many volts of potential difference must an electron be accelerated to achieve a wavelength of 0.28 nm? ( h = 6.63×10-34Js; me= 9.11×10-31kg ) (A) 12V (B) 16V (C) 19V (D) 31V (E) 34V ...
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This note was uploaded on 04/04/2010 for the course SFSEFSEF 489484 taught by Professor Fesfesf during the Winter '08 term at A.T. Still University.

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