【GR9677】 The Solution for GRE Physics Practice Test [21-40]

The Solution for GRE Physics Practice Test [21-40]

 

추천글 : 【GRE】 Solution for GRE Physics Practice Test 

---

 

21. The period of a physical pendulum is 2π√(I / mgd), where I is the moment of inertia about the pivot point and d is the distance from the pivot to the center of mass. A circular hoop hangs from a nail on a barn wall. The mass of the hoop is 3 kilo-grams and its radius is 20 centimeters. If it is displaced slightly by a passing breeze, what is the period of the resulting oscillations?

 

 

⑴ answer: C

⑵ 계산 과정 : 질량 m과는 무관함 

 

 

 

22. The curvature of Mars is such that its surface drops a vertical distance of 2.0 meters for every 3600 meters tangent to the surface. In addition, the gravitational acceleration near its surface is 0.4 times that near the surface of Earth. What is the speed a golf ball would need to orbit Mars near the surface, ignoring the effects of air resistance?

 

 

⑴ answer: C

⑵ 계산 과정

 

 

 

 

23. Suppose that the gravitational force law between two massive objects were F₁₂ = r₁₂ Gm₁m₂ / r₁₂^2+ϵ where ϵ is a small positive number. Which of the following statements would be FALSE?

 

 

⑴ answer: D

⑵ 케플러 법칙 

🄐 보존력이 정의되면 역학적 에너지 보존법칙이 정의됨 

🄑 각운동량 보존법칙은 c := r(t) × r'(t)라 두면, c'(t) = r'(t) × r'(t) + r(t) × r"(t) = r(t) × r"(t) = 0

🄒, 🄔 약식 계산 : 구심력이 중력인 정적 원형 궤도 상황을 가정하면,

 

 

🄓 타원 궤도의 법칙은 중력이 거리의 제곱에 반비례하는 중심력이라는 사실과 연결됨 

 

 

24. Two identical conducting spheres, A and B, carry equal charge. They are initially separated by a distance much larger than their diameters, and the force between them is F. A third identical conducting sphere, C, is uncharged. Sphere C is first touched to A, then to B, and then removed. As a result, the force between A and B is equal to

 

 

⑴ answer: D

⑵ (Q_A, Q_B) = (Q, Q) → (Q/2, Q) → (Q/2, 3Q/4)

⑶ F = kQ2 

⑷ F' = k(Q/2)(3Q/4) = 3F / 8

 

 

25. Two real capacitors of equal capacitance (C₁ = C₂) are shown in the figure below. Initially, while the switch S is open, one of the capacitors is uncharged and the other carries charge Q₀. The energy stored in the charged capacitor is U₀. Sometime after the switch is closed, the capacitors C₁ and C₂ carry charges Q₁ and Q₂, respectively; the voltages across the capacitors are V₁ and V₂; and the energies stored in the capacitors are U₁ and U₂. Which of the following statements is INCORRECT?

 

 

⑴ answer: E

⑵ 커패시터 

⑶ Q = CV이고 V가 공통이므로 Q₀ = Q₁ = Q₂ → Q₀ = (Q₁ + Q₂) / 2

⑷ U = (1/2)V²이고 V가 공통이므로 U₀ = U₁ = U₂ → 2U₀ = U₁ + U₂ 

 

 

26. A series RLC circuit is used in a radio to tune to an FM station broadcasting at 103.7 MHz. The resistance in the circuit is 10 ohms and the inductance is 2.0 microhenries. What is the best estimate of the capacitance that should be used?

 

 

⑴ answer: C

⑵ RLC 회로 : ω² = 1 / LC → 1 / ((2 × π × 103.7 × 10⁶)² × 2 × 10^-6) = 1.18 pF

 

 

27. In laboratory experiments, graphs are employed to determine how one measured variable depends on another. These graphs generally fall into three categories: linear, semilog (logarithmic versus linear), and log-log. Which type of graph listed in the third column below would NOT be the best for plotting data to test the relationship given in the first and second columns?

 

 

⑴ answer: D

⑵ linear : Y = aX + b의 형태

⑶ semilog : log Y = aX + b의 형태

⑷ log-log : log Y = a log X + b의 형태 

🄓 linear라기보다는 반비례(inversely linear)

 

 

28. The figure below represents the trace on the screen of a cathode ray oscilloscope. The screen is graduated in centimeters. The spot on the screen moves horizontally with a constant speed of 0.5 centimeter/millisecond, and the vertical scale is 2 volts/centimeter. The signal is a superposition of two oscillations. Which of the following are most nearly the observed amplitude and frequency of these two oscillations?

 

 

⑴ answer: D

⑵ 파동의 개념 

⑶ 큰 파동 : f1 = v1 / λ1 = 0.5 cm/ms / 6 cm = 1000/12 = 83 Hz. 진폭은 y축으로 1.25 cm와 대응되는 2.5 V

⑷ 작은 파동 : f2 = v2 / λ2 = 0.5 cm/ms / 1 cm = 1000/2 = 500 Hz. 진폭은 큰 파동의 절반인 1.25 V 

 

 

29. I

 

⑴ answer: E

⑵

 

 

30. In

 

⑴ answer: C

⑵ 

 

 

31. A

 

⑴ answer: E

⑵

 

 

32. The

 

⑴ answer: B

⑵

⑶

 

 

33. A 

 

⑴ answer: C

⑵ 

 

 

34. T

 

⑴ answer: D

⑵ 

 

 

35. S

 

⑴ answer: A

⑵ 

 

 

36. The

 

⑴ answer: D

⑵ 

 

 

37. The

 

⑴ answer: D

⑵

 

 

38. Con

 

⑴ answer: D

⑵

 

 

39. Wh

 

⑴ answer: E

⑵ 

 

 

40. A 

 

⑴ answer: A

⑵

 

입력: 2026.05.05 23:26