31. An object of mass m is sliding with speed v at some instant across a level tabletop, with which its coefficient of kinetic friction is µ. It then moves through a distance d and comes to rest. Which of the following equations for the speed v is reasonable? (Gravitational acceleration is g)
(A) (2μgd) ^1/2
(B) (mgd) ^1/2
(C) (2μmgd) ^1/2
(D) (2μgd) -^1/2
(E) (2μd) ^1/2

27. Which of the following electron configurations is incorrect? (A)S2– : 1s22s22p63s23p6(B) Na+:1s2 2s 2 2p6(C) Ga: 1s2 2s2 2p63s23p64s23d10(D)V:1s22s22p63s23p64s23d3(E)I: 1s22s22p63s23p64s2 3d104p65s24d105p5

28. How many moles of Ca(NO3)2 must be added to 0.5 L of a 0.4 M KF solution to begin precipitation of CaF2? For CaF2, Ksp = 4.0 ✖ 10–11.(A) 2.0 ✖ 10–12(B) 1.0 ✖ 10–10 (C) 2.0 ✖10–10(D)1.0 ✖ 10–9(E) 5.0 ✖10–9

29. For the reaction below, Which of the following statements is true? (A) This reaction is endothermic.(B) △G for this reaction has to be negative at all temperatures. (C) Kp is smaller than 1.00 when△G for the reaction is negative. (D) ΔS° for this reaction is negative. (E) All of the above statements are true.

30. Which of the following species needs resonance to adequately describe its structure? (A) H2O(B) CO3 2– (C) NH3 (D) HCN (E) NH4 +

32. A force acting on an object moving along the x axis is given by Fx = (14x − 3x2 ) N, where x is in m. How much work is done by this force as the object moves from x = −1 m to x = +2 m? (A) +12 J (B) +28 J (C) +40 J (D) +42 J (E) −28 J

33. The block shown in the figure is released from rest when the spring is stretched a distance d. If k = 75 N/m, m = 0.5 kg, d =10 cm, and the coefficient of kinetic friction between the block and the horizontal surface is equal to 0.25, what is the speed of the block when it first passes through the position for which the spring is unstretched. (Gravitational acceleration g = 10 m/s2 )(A) 0.53 m/s (B) 0.92 m/s (C) 1.00 m/s (D) 1.22 m/s (E) 1.44 m/s k 

34. A police crime lab is trying to determine whether someone was murdered or died as a result of an accident. The victim was struck in the temple by a 4 kg sculpture that is alleged to have fallen off a bookcase. The sculpture presumably fell a distance of 20 m and the corner that struck him had an area of 0.25 cm2 . If the time for the sculpture to stop was 1 ms, the pressure on his temple, in N/m2 , was ______. (Gravitational acceleration g = 10 m/s2 ) (A) 3.2 × 105 (B) 1.6 × 106 (C) 3.2 × 106 (D) 1.6 × 109 (E) 3.2 × 109

35. A 3 kg particle moves to the right at 4 m/s as shown in the figure. The magnitude of its angular momentum in (kg ● m2 /s) about the point O is ______.  (A) 0 (B) 48 (C) 72 (D) 144 (E) 1728

36. A particle moves in the xy plane, starting from the origin at t = 0 with an initial velocity having an x component of 20 m/s and a y component of −15 m/s. The particle experiences an acceleration in the x direction, given by ax = 4 m/s2 . What is the total velocity at any time? (A)(B)(C)(D)(E)

37. A grindstone increases in an angular speed from 4 rad/s to 12 rad/s in 4 s. Through what angle does it turn during that time interval if the angular acceleration is constant? (A) 8 rad (B) 12 rad (C) 16 rad (D) 32 rad (E) 64 rad