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Passage VI Study 2 The students looked up the coefficient of kinetic fric- 36, Based on the results of the 2 studies, for each combina- tion of plane and block tested, compared to the coeffi- 39, In Study J, why did the block in a given trial begin to Some students performed studies of static friction (the tion (Uk, a measure of the frictional force between a plane cient of kinetic friction, the coefficient of static move? Once 0 became equal to Os, the; frictional force between 2 surfaces that are at rest relative and a sliding block) for each combination of plane and friction was; A, gravitational force on the block was decreased to each other) and kinetic friction (the frictional force block, For each trial, 0 was initially 45, Once a block was placed on the plane and released, it began to slide, The stu- F. always greater, enough such that the frictional force could acceler- between 2 surfaces that are sliding past each other), G, always less, ate the block down the plane, dents reduced 0 until it reached its critical value, Of, the H, always equal, B, gravitational force on the block was increased Study 1 angle at which the block's speed down the incline became J. sometimes greater and sometimes less, enough such that the frictional force could acceler- The students obtained three identically sized planes, constant (see Table 2), ate the block down the plane, each made of either glass, metal, or wood, and three 1,0 kg 37. Can it be determined from the results of the studies C, frictional force on the block was decreased enough such that the gravitational force could accelerate blocks, each made of either glass, metal, or wood, They whether the value of 9 for a given block depended on looked up the coefficient of static friction (Us, a measure of Table 2 the mass of that block? the block down the plane, D. frictional force on the block was increased enough the frictional force between a plane and a motionless Block A. Yes, because the blocks varied in mass. such that the gravitational force could accelerate block) for each combination of plane and block to be Trial Plane HK Oc tested, With a plane in the horizontal position (0 = 09, B. Yes, because the blocks all had the same mass. the block down the plane, where I was the angle between the plane and the table) and glass glass 0,40 220 C. No, because the blocks varied in mass, a block at the starting line (see Figure 1), the students 0.25 149 D. No, because the blocks all had the same mass. glass metal increased 0 until the moment the block began to slide, glass wood | 0,05 30 They recorded the angle at that moment as Os (see Table 1), metal metal 0.58 30 38. In Study 2, the students performed the minimum 11 metal wood 0.19 119 number of trials necessary to test each substance with 40, In each trial of Study 2, 0 was initially 45, Based on wood wood 0.25 140 itself and with every other substance listed in Table 2. the results of Study 1, which of the following state- block starting line Suppose that they had included a fourth plane and a ments best explains why this initial value of O was fourth 1,0 kg block in Study 2, each made of concrete, chosen? For each combination of plane and block -plane What minimum number of trials would have been tested in Study 2, this initial value of 0 was; required in Study 2 to test each of the 4 substances? 0 =0' . .............".".. 6 equal to Oc. G. 10 G. less than Oc. start of a trial during a trial H. 14 H. less than Os. J. 18 J. greater than Os. Figure I 34. Based on the results of the studies, the absolute value of the difference between Os and c was greatest for which of the following pairs of trials? END OF TEST 4 Table 1 F. Trials I and 7 G, Trials 2 and 8 STOP! DO NOT RETURN TO ANY OTHER TEST. Trial Plane Block H. Trials 3 and 9 J. Trials 4 and 10 glass glass 0,93 439 glass metal 0,60 310 glass wood 0,19 1 10 35. Based on the results of Study 2, as HK increased, Oc: QUAUNE metal metal 0,75 370 A, increased only metal wood 0.53 280 B, decreased only, wood wood 0.34 190 C. increased and then decreased, D, decreased and then increased