32. A part of the square that has sides of length L is removed from one corner. The center of mass of the remainder moves from C to C'. The displacement of the x coordinate of the center of mass (from C to C') is ______.

(A) (2/3)L
(B) (1/6)L
(C) (1/8)L
(D) (1/10)L
(E) (1/12)L

28. For the reaction 3A(g) + 2B(g) → 2C(g) + 2D(g), the following data was collected at constant temperature. Determine the correct rate law for this reaction.  (A) Rate = k[A][B] (B) Rate = k[A][B]2 (C) Rate = k[A]3 [B]2 (D)(E) Rate = k[A]2 [B]

29. What is the number of the half-lives required for a radioactive element to decay to about 6% of its original activity? (please choose the nearest number) (A) 2 (B) 3 (C) 4 (D) 5 (E) 6

30. Identify the element of Period 2 which has the following successive ionization energies, in kJ/mol.   (A) Li (B) B (C) O (D) Ne (E) None of these

31. Based on an order-of-magnitude estimate, what is the radius of the Earth in the unit of kilometer (km)? Hint: The meter was originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole along a great circle. (A) 2 (B) 4 (C) 6 (D) 8 (E) 10

複選題33. The string and the pulley are massless, and the coefficient of static and kinetic frictions are 0.2 and 0.1, respectively, for both table 1 (T1) and 2 (T2). If m1 = 2 kg, m2 = 3 kg, and m = 1.5 kg, find the acceleration of m. (Gravitational acceleration g = 10 m/s2 )  (AB) 7.7 m2 /s (AC) 8.7 m2 /s (AD) 9.7 m2 /s (AE) 10.7 m2 /s (BC) 11.7 m2 /s (BD)一律送分

34. Aluminum Rod #1 has a length L and a diameter d. Aluminum Rod #2 has a length 2L and a diameter 2d. If Rod #1 is under tension T and Rod #2 is under tension 2T, how do the changes in length of the two rods compare? (A) They are the same. (B) Rod #1 has double the change in length that Rod #2 has. (C) Rod #2 has double the change in length that Rod #1 has. (D) Rod #1 has quadruple the change in length that Rod #2 has. (E) Rod #2 has quadruple the change in length that Rod #1 has.

35. A toy car is running on a banked circular track of radius 10 m, as shown below. If the car weighs 5 kg and on wet ice, find the maximum velocity for the car to keep on the track without skid. (Gravitational acceleration g = 10 m/s2 , cos30° = 0.87, cos60° = 0.5)  (A) 5.4 m/s (B) 7.6 m/s (C) 9.4 m/s (D) 12.6 m/s (E) 15.7 m/s

36. A small block of mass m rests on the sloping side of a triangular block of mass M which itself rests on a horizontal table as shown in the figure below. Assuming all surfaces are frictionless, determine the magnitude of the force F that must be applied to M so that m remains in a fixed position relative to M. Hint: 1. Take x and y axes horizontal and vertical. 2. Focus at the object m. (A) mg sinθ (B) mg tanθ (C) (m+M)g tanθ(D) (m+M)g sinθ(E) None of these

37. The four tires of an automobile are inflated to a gauge pressure of 2.0 × 105 N/m2 (29 psi). Each of the four tires has an area of 0.024 m2 that is in contact with the ground. Determine the weight of the auto. (A) 4.80 × 103N (B) 1.92 × 104N (C) 7.68 × 104N (D) 8.33 × 106N (E) 2.08 × 107N

38. A 2-kg block slides down a frictionless incline from point A to point B. A force (magnitude P = 3 N) acts on the block between A and B, as shown in the figure Points A and B are 2 m apart. If the kinetic energy of the block at A is 10 J, what is the kinetic energy of the block at B? (Gravitational acceleration g = 10 m/s2 ) (A) 17 J (B) 20 J (C) 24 J (D) 27 J (E) 37 J