Keep trying until you find the correct answer.

1. A rectangular block is on a rough flat surface. It is not moving.

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2. A rectangular block is on a rough flat surface. It is moving to the left and slowing down.

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3. A rectangular block is on a rough flat surface. It is moving to the right and slowing down.

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4. A rectangular block is on a rough inclined surface. It is not moving.

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5. A rectangular block is on a rough inclined surface. It is not moving but is just about to slip.

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6. A rectangular block is on a rough inclined surface. It is moving down the incline and moves faster as it travels.

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7. A rectangular block is on a rough inclined surface. It is moving down the incline and moves slower as it travels.

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8. A rectangular block is on a rough inclined surface. It is moving down the incline at constant speed.

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9. A rectangular block is on a rough inclined surface. It is moving up the incline and moves slower as it travels.

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10. A rectangular block is on a smooth frictionless flat surface. It is not moving.

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11. A rectangular block is on a smooth frictionless flat surface. It is moving to the right at constant speed.

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12. A rectangular block is on a smooth frictionless flat surface. It is moving to the left at constant speed.

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13. A rectangular block is on a smooth frictionless flat surface. It is being pulled to the right by a horizontal string.

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14. A rectangular block is on a smooth frictionless flat surface. It is being pulled to the left by a horizontal string.

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15. A rectangular block is on a rough flat surface. It is being pulled to the right by a horizontal string. It is not moving.

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16. A rectangular block is on a rough flat surface. It is being pulled to the right by a horizontal string. It is just about to start moving.

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17. A rectangular block is on a rough flat surface. It is being pulled to the right by a horizontal string. It is moving at constant speed.

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18. A rectangular block is on a rough flat surface. It is being pulled to the right by a horizontal string. It moves faster as it travels.

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19. A rectangular block is on a rough flat surface. It is being pulled to the left by a horizontal string. It is not moving.

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20. A rectangular block is on a rough flat surface. It is being pulled to the left by a horizontal string. It is just about to start moving.

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21. A rectangular block is on a rough flat surface. It is being pulled to the left by a horizontal string. It is moving at constant speed.

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22. A rectangular block is on a rough flat surface. It is being pulled to the left by a horizontal string. It moves faster as it travels.

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23. A rectangular block is on a rough inclined surface. It is being pulled by a string parallel to, and up, the incline. It is just about to start moving up the incline.

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24. A rectangular block is on a rough inclined surface. It is being pulled by a string parallel to, and up, the incline. It is just about to start sliding down the incline.

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25. A rectangular block is on a rough inclined surface. It is being pulled by a string parallel to, and up, the incline. It is moving at constant speed up the incline.

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26. A rectangular block is on a rough inclined surface. It is being pulled by a string parallel to, and up, the incline. It is moving at constant speed down the incline.
    
    

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27. A rectangular block is on a rough inclined surface. It is being pulled by a string parallel to, and up, the incline. It moves up the incline traveling faster as it goes.

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28. A rectangular block is on a rough inclined surface. It is being pulled by a string parallel to, and up, the incline. It moves down the incline traveling faster as it goes.

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29. A rectangular block is on a rough inclined surface. It is being pulled by a string parallel to, and down, the incline. It is not moving.

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30. A rectangular block is on a rough inclined surface. It is being pulled by a string parallel to, and down, the incline. It is just about to start moving.

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31. A rectangular block is on a rough inclined surface. It is being pulled by a string parallel to, and down, the incline. It is moving at constant speed down the incline.

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32. A rectangular block is on a rough inclined surface. It is being pulled by a string parallel to, and down, the incline. It moves down the incline traveling faster as it goes.

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33. A rectangular block is on the floor of an elevator. The elevator is moving upwards at constant velocity. We are interested in the block only.

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34. A rectangular block is on the floor of an elevator. The elevator is moving upwards and is increasing speed. We are interested in the block only.

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35. A rectangular block is on the floor of an elevator. The elevator is moving upwards and is slowing down. We are interested in the block only.

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36. A rectangular block is on the floor of an elevator. The elevator is moving downwards at constant velocity. We are interested in the block only.

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37. A rectangular block is on the floor of an elevator. The elevator is moving downwards and is increasing speed. We are interested in the block only.

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38. A rectangular block is on the floor of an elevator. The elevator is moving downwards and is slowing down. We are interested in the block only.

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39. A rectangular block is hanging by a string from the ceiling of an elevator. The elevator is moving upwards at constant velocity. We are interested in the block only.

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40. A rectangular block is hanging by a string from the ceiling of an elevator. The elevator is moving upwards and is increasing speed. We are interested in the block only.

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    6.   ?    

41. A rectangular block is hanging by a string from the ceiling of an elevator. The elevator is moving upwards and is slowing down. We are interested in the block only.

    1.   ?    
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    5.   ?    
    6.   ?    

42. A rectangular block is hanging by a string from the ceiling of an elevator. The elevator is moving downwards at constant velocity. We are interested in the block only.

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    3.   ?    
       
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    5.   ?    
    6.   ?    

43. A rectangular block is hanging by a string from the ceiling of an elevator. The elevator is moving downwards and is increasing speed. We are interested in the block only.

    1.   ?    
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    3.   ?    
       
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    5.   ?    
    6.   ?    

44. A rectangular block is hanging by a string from the ceiling of an elevator. The elevator is moving downwards and is slowing down. We are interested in the block only.

    1.   ?    
    2.   ?    
    3.   ?    
       
    4.   ?    
    5.   ?    
    6.   ?    

45. A rectangular block is hanging by a string. The block is moving upwards at constant velocity. Ignore air resistance.

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    6.   ?    

46. A rectangular block is hanging by a string. The block is moving upwards and is increasing speed. Ignore air resistance.

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    6.   ?    

47. A rectangular block is hanging by a string. The block is moving upwards and is slowing down. Ignore air resistance.

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    6.   ?    

48. A rectangular block is hanging by a string. The block is moving downwards at constant velocity. Ignore air resistance.

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    5.   ?    
    6.   ?    

49. A rectangular block is hanging by a string. The block is moving downwards and is increasing speed. Ignore air resistance.

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    3.   ?    
       
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    5.   ?    
    6.   ?    

50. A rectangular block is hanging by a string. The block is moving downwards and is slowing down. Ignore air resistance.

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    6.   ?    

51. A toy car is on a track. Currently it is moving just over a curved peak or hill on the track. Treat the track as frictionless and ignore air resistance.

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52. A toy car is on a track. Currently it is moving just around a curved trough or valley in the track. Treat the track as frictionless and ignore air resistance.

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    5.   ?    

53. A toy car is on a track. Currently it is moving on the underside of a loop on the track at the highest point in the loop. Treat the track as frictionless and ignore air resistance.

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    10.   ?    

54. A rectangular block is tied to a string. The string is used to twirl the block in a vertical circle. The block is currently at the very top of the circle. Ignore air resistance.

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    10.   ?    

55. A rectangular block is tied to a string. The string is used to twirl the block in a vertical circle. The block is currently at the very bottom of the circle. Ignore air resistance.

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    5.   ?    

56. A rectangular block is thrown into the air. Currently it is moving upwards. Ignore air resistance.

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    6.   ?    

57. A rectangular block is thrown into the air. Currently it is moving downwards. Ignore air resistance.

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    5.   ?    
    6.   ?    

58. A rectangular block is thrown into the air. Currently it is at the farthest height it reaches. Ignore air resistance.

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    6.   ?    

59. A rectangular block is on a sheet of paper which is in turn on a table. Both the paper and the table have rough surfaces. The sheet of paper is pulled to the right and the block moves with the paper at constant speed with respect to the table. We are interested in the block.

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    7.   ?    
    8.   ?    

60. A rectangular block is on a sheet of paper which is in turn on a table. Both the paper and the table have rough surfaces. The sheet of paper is pulled to the right and the block moves with the paper, both block and paper increasing speed with respect to the table. We are interested in the block.

    1.   ?    
    2.   ?    
    3.   ?    
       
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    6.   ?    
       
    7.   ?    
    8.   ?    
    9.   ?    
       
    10.   ?    
    11.   ?    
    12.   ?    

61. A rectangular block is on a sheet of paper which is in turn on a table. Both the paper and the table have rough surfaces. The sheet of paper is pulled to the right and the block moves with the paper, both block and paper increasing speed with respect to the table. The block is just about to slip relative to the paper. We are interested in the block.

    1.   ?    
    2.   ?    
    3.   ?    
       
    4.   ?    
    5.   ?    
    6.   ?    
       
    7.   ?    
    8.   ?    
    9.   ?    
       
    10.   ?    
    11.   ?    
    12.   ?    

62. A rectangular block is on a sheet of paper which is in turn on a table. Both the paper and the table have rough surfaces. The sheet of paper is pulled to the right. The block also moves to the right with increasing speed but is slipping on the surface of the paper. We are interested in the block.

    1.   ?    
    2.   ?    
    3.   ?    
       
    4.   ?    
    5.   ?    
    6.   ?    
       
    7.   ?    
    8.   ?    
    9.   ?    
       
    10.   ?    
    11.   ?    
    12.   ?    

63. A rectangular block is on a sheet of paper which is in turn on a table. Both the paper and the table have rough surfaces. The sheet of paper is pulled to the left and the block moves with the paper at constant speed with respect to the table. We are interested in the block.

    1.   ?    
    2.   ?    
    3.   ?    
       
    4.   ?    
    5.   ?    
    6.   ?    
       
    7.   ?    
    8.   ?    

64. A rectangular block is on a sheet of paper which is in turn on a table. Both the paper and the table have rough surfaces. The sheet of paper is pulled to the left and the block moves with the paper, both block and paper increasing speed with respect to the table. We are interested in the block.

    1.   ?    
    2.   ?    
    3.   ?    
       
    4.   ?    
    5.   ?    
    6.   ?    
       
    7.   ?    
    8.   ?    
    9.   ?    
       
    10.   ?    
    11.   ?    
    12.   ?    

65. A rectangular block is on a sheet of paper which is in turn on a table. Both the paper and the table have rough surfaces. The sheet of paper is pulled to the left and the block moves with the paper, both block and paper increasing speed with respect to the table. The block is just about to slip relative to the paper. We are interested in the block.

    1.   ?    
    2.   ?    
    3.   ?    
       
    4.   ?    
    5.   ?    
    6.   ?    
       
    7.   ?    
    8.   ?    
    9.   ?    
       
    10.   ?    
    11.   ?    
    12.   ?    

66. A rectangular block is on a sheet of paper which is in turn on a table. Both the paper and the table have rough surfaces. The sheet of paper is pulled to the left. The block also moves to the left with increasing speed but is slipping on the surface of the paper. We are interested in the block.

    1.   ?    
    2.   ?    
    3.   ?    
       
    4.   ?    
    5.   ?    
    6.   ?    
       
    7.   ?    
    8.   ?    
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    10.   ?    
    11.   ?    
    12.   ?