95年 - [無官方正解]95 國立清華大學_碩士班招生考試：普通物理#138611

1. How fast is it moving? (A) 2.6m/s (B) 5.1m/s (C) 10.3m/s (D) 20.4m/s (E) None of the above

2. How fast is it spinning? (A) 3.0 rad/s (B) 6.2 rad/s (C) 11.9rad/s (D) 23.5 rad/s (E) None of the above

3. How much string (length) has unwrapped from around the rim? (4%) (A) 4.5m (B) 9m (C) 18m (D) 36m (E) None of the above

4. The gravitational force on the beam is (A) -2Tcotθ ĵ (B) -2Tsinθ ĵ (C) -2Tcosθ ĵ (D) -2Ttanθ ĵ (E) None of the above

5. The force on the beam from the hinge is (A) 2Tcosθ î + T ĵ (B) Tsinθ î + 2Tcotθ ĵ (C) Tcosθ î + 2Ttanθ ĵ (D) T î + 2Tcotθ ĵ (E) None of the above

6. What frequency is heard on the other train if the wind is blowing at v_w toward the whistle and away from the listener? (A) (B)(C) (D) (E) None of the above

7. What frequency is heard if the wind direction is reversed? (A) (B) (C)(D) (E) None of the above

 8. At what distance x does the stream strike the floor? (A) (B)(C)(D) (E) None of the above

9. At what depth should a hole be made to maximize x? (A) H (B) H/2 (C) H/4 (D) H/8 (E) None of the above

10. What is the pressure in the container? (A) 4p₀/3 (B) 3p₀/4 (C) 7p₀/5 (D) 5p₀/7 (E) None of the above

11. What is the entropy increase of the system? (A)(3ln5+4ln1.25) (B)(4ln5+3ln1.25) (C)(3ln5+4ln1.25) (D)(4ln5+3ln1.25) (E) None of the above

 12. What is the sphere's total charge? (A) 2πρ_sR² (B) 3πρ_sR (C) πρ_sR² (D) πρ_sR³ (E) None of the above

13. What is the magnitude E of the electric field at r=R/2? (A) (B) (C) (D) (E) None of the above

14. Figure 4 shows, in cross section, two solid spheres with uniformly distributed charge throughout their volumes. Each has radius R. Point P lies on a line connecting the centers of the spheres, at radial distance R/2.00 from the center of sphere 1. If the net electric field at point P is zero, what is the ratio q₂/q₁ of the total charge q₂ in sphere 2 to the total charge q₁ in sphere 1?

(A) 9/8 (B) 2/3 (C) 7/5 (D) 11/6 (E) None of the above

15. Figure 5 shows a cross section of a long thin ribbon of width w that is carrying a uniformly distributed total current i into the page. What is the magnetic field B at a point P in the plane of the ribbon at a distance d from its edge?

(A)(B) (C) (D) (E) None of the above

16. The current through the inductor at time t is: (A) ie^-Rt/L(B) i(1-e^-Rt/2L) (C) ie^-Rt/2L (D) i(1-e^-Rt/L) (E) None of the above

17. At what time is the current through the resistor equal to the current through the inductor? t= (A) 2Lln2/3R (B) Lln2/3R (C) Lln2/R (D) 2Lln2/R (E) None of the above

18. In an x-ray diffraction measurement, if first-order reflection occurs in a crystal at Bragg angle θ₁, at what Bragg angle θ₂ does second-order reflection occur from the same family of reflecting planes? θ₂= (A) 2θ₁ (B) 2sinθ₁ (C) sin⁻¹(2θ₁) (D) sin⁻¹(2sinθ₁) (E) None of the above

 19. What is the energy of the electron? (A) h²/2m_eλ² (B) h/2m_eλ (C) h²/m_eλ² (D) h/m_eλ (E) None of the above

20. What is the energy of the photon? (A) c/hλ (B) hc/λ (C) hλ/c (D) λ/hc (E) None of the above