所屬科目:研究所、轉學考(插大)◆普通物理學
1. What is the value ofπ(8.104)2, written with the correct number of significant figures? (A)206.324,(B)206.323,(C)206.3,(D) 206,(E) 200.
2. Block A (0.40 kg) and block B (0.30 kg) are on a frictionless table (see figure). Spring 1 connects block A to a frictionless peg at O and spring 2 connects block A and block B. When the blocks are in uniform circular motion about O, the springs have lengths of 0.60 m and 0.40 m, as shown. The springs are ideal and massless, and the linear speed of block B is 2.0 m/s. If the spring constant of spring 1 is equal to 30 N/m, the unstretched length of spring 1 is closest to (A) 0.51 m, (B)0.53 m, (C) 0.55 m, (D) 0.54 m, (E) 0.52 m. 00000000003 0.60 m heQ00- -0.40 m-
4.Ekapluto is an unknown planet that has two moons in circular orbits. The table summarizes the hypothetical data about the moons. (G = 6.67 x 10-11 Nㆍm2/kg2) The mass of Ekapluto is closest to (A)1.0 x 1023 kg, (B) 3.0 x 1023 kg, (C) 1.0 x 1024 kg, (D) 1.0 x 1022 kg, (E) 3.0 x 1022 kg.
5. A nonuniform electric field is directed along the x-axis at all points in space. This magnitude of the field varies with x, but not with respect to y or z. The axis of a cylindrical surface, 0.80 m long and 0.20 m in diameter, is aligned parallel to the x-axis, as shown in the figure. The electric fields E1 and E2, at the ends of the cylindrical surface, have magnitudes of 9000 N/C and 5000 N/C respectively, and are directed as shown. (ε = 8.85 x 10-12 C2/N ㆍm2) The charge enclosed by the cylindrical surface is closes(A) -2.4 nC.(B) -4.8 nC.(C)-1.1 nC.(D)4.8 nC.(E) 1.1 nc.
6. In the figure, two masses, M = 16 kg and m = 12.80 kg, are connected to a very light rigid bar and are attached to an ideal massless spring of spring constant 100 N/m. The system is set into oscillation with an amplitude of 78 cm. At the instant when the acceleration is at its maximum, the 16-kg mass separates from the 12.80-kg mass, which then remains attached to the spring and continues to oscillate. What will be the amplitude of oscillation of the 12.80-kg mass? (A) 35 cm, (B) 62 cm, (C) 98 cm, (D) 78 cm, (E) 180 cm.
7. A rectangular block twice as high as it is wide is resting on a board. The coefficient of static friction between board and incline is 0.46. If the board's incline angle is gradually increased,(A) the block will first tip over than slide. (B) the block will first slide than tip over. (C) will the block first tip over or begin sliding depends on its moment of inertia. (D) will the block first tip over or first begin sliding depends on the coefficient of kinetic friction between board and incline. (E) None of the above.
8. A paint sprayer pumps air through a constriction in a 2.50-cm diameter pipe, as shown in the figure. The flow causes the pressure in the constricted area to drop and paint rises up the feed tube and enters the air stream. The speed of the air stream in the 2.50-cm diameter sections is 5.00 m/s. The density of the air is 1.29 kg/m3, and the density of the paint is 1200 kg/m3 . We can treat the air and paint as incompressible ideal fluids. What is the maximum diameter of the constriction that will allow the sprayer to operate?(A)12.2mm,(B)9.65 mm, (C) 14.3 mm, (D) 4.05 mm, (E) 8.07 mm.
11. A heat engine performs the reversible cycle abca with 9.0 moles of an ideal gas, as shown in the figure. Path ca is an adiabatic process. The temperatures at points a and b are 300 K and 500 K, respectively. The volume at point c is 0.20 m3. The adiabatic constant of the gas is 1.60. The thermal efficiency of this engine is closest to (A)0.13, (B) 0.10, (C) 0.16, (D) 0.07, (E) 0.19.
12. A cylinder contains 1.2 moles of ideal gas, initially at a temperature of 116℃. The cylinder is provided with a frictionless piston, which maintains a constant pressure of 6.4 x 105 Pa on the gas. The gas is cooled until its temperature has decreased to 27℃. For the gas Cy= 11.65 J/molㆍK, and the ideal gas constant R = 8.314 J/mol.K. (A) The work done by the gas during this process is 890 J. (B) The work done on the gas during this process is 890 J. (C) The change in the internal (thermal) energy of the gas during this process is +1200 J. (D) The heat transferred from the gas during this process is -1200 J. (E) The heat transferred to the gas during this process is +2100 J.
15. In the circuit shown in the figure, the capacitors are initially uncharged. The switch is first thrown to position A and kept there for a long time. It is then thrown to position B. Let the charges on the capacitors be Q1, Q2, and Q3 and the potential differences across them be V1, V2, and V3. Which of the following conditions must be true with the switch in position B?(A) Q1=Q2=Q3,(B) V2=V2=V3,(C)V1+V2=V3,(D) Q1+Q2 =Q3, (E) V3 =V0
16. Two long conducting cylindrical shells are coaxial and have radii of 20 mm and 80 mm. The electric potential of the inner conductor, with respect to the outer conductor, is +600 V. What is the maximum electric field magnitude between the cylinders? (k = 1/4πεo = 8.99 x 109Nㆍm2/C2) (A) 22,000 V/m, (B) 18,000 V/m, (C) 10,000 V/m, (D) 14,000 V/m, (E) 26,000 VIm.
18. A long straight very thin wire on the y-axis carries a 10-A current in the positive y-direction. A circular loop 0.50 m in radius, also of very thin wire and lying in the yz-plane, carries a 9.0-A current, as shown. Point P is on the positive x-axis, at a distance of 0.50 m from the center of the loop. What is the magnetic field vector at point P due to these two currents? (μ0 =4πx 10-7 T m/A) (A) zero (B) -8.0 x10-6Tk (C)(+4.0x10-6T)i- (4.0 x10-6T)k (D) (-8.0x10-6T)i - (8.0 x 10-6T)k (E)(-4.0x10-6T)i-(4.0 x10-6T)k
19. Wire is wound on a square frame, 30 cm by 30 cm, to form a coil of 7 turns. The frame is mounted on a horizontal shaft through its center (perpendicular to the plane of the diagram), as shown in the figure. The coil is in clockwise rotation, with a period of 0.060 s. A uniform, horizontal, magnetic field of magnitude 0.40 T is present. At a given instant, the plane of the coil forms a 60° angle with the horizontal, as shown. At that instant, what is the magnitude of the emf induced in the coil? (A) 2.1 V,(B) 23 V, (C) 26 V, (D) 3.6 V, (E) 13 V.
20. An LRC series circuit has R = 15.0 Ω, L = 25.0 mH, and C = 30.0 μF. The circuit is connected to a 120-V (rms) ac source with frequency 200 Hz. (A) The impedance of the circuit is 163 Ω, (B) The rms current in the circuit is 7.16 A, (C) The rms voltage across the resistor is 110V, (D) The rms voltage across the inductor is 239 V, (E) The rms voltage across the capacitor is 123 V
21.Some properties of glass are listed here. glass window pane is 2.7 m high, 2.4 m wide, and 2.0 mm thick. The temperature at the inner surface of the glass is 22℃ and at the outer surface 4.0℃. How much heat is lost each hour through the window under steady state conditions? (A)1.7x108J,(B)4.7x104J,(C)1.7x106J,(D) 1.7 x 105 J,(E)4.7 x 101 J.
23. A microwave oven operates with sinusoidal microwaves at a frequency of 2400 MHz. The height of the oven cavity is 25 cm and the base measures 30 cm by 30 cm. Assume that microwave energy is generated uniformly on the upper surface of the cavity and propagates directly downward toward the base. The base is lined with a material that completely absorbs microwave energy. The total microwave energy content of the cavity is 0.50 μJ. What is the amplitude of the electric field? (c = 3.00 x 108m/s, μ0 = 4πx 10-7 T m/A, ε0 = 8.85 x 10-12 C2/N m2)(A) 2500 V/m, (B) 1900 V/m, (C) 2200 V/m, (D) 2800 V/m, (E) 1600 V/m.