The frictional force of the floor on a large suitcase is least when the suitcase is
A. pushed by a force parallel to the floor.
B. dragged by a force parallel to the floor.
C. pulled by a force directed at an angle ? above the floor.
D. pushed by a force directed at an angle ? into the floor.
E. turned on its side and pushed by a force parallel to the floor.
Answer: C
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