摘要 |
Among other things, a force is applied, at a first location in a medium and at a first time, to cause an object to move in a direction along the medium. At a later, second time, a force is applied at a second location, which is farther along the direction in which the object is moving, to cause the object to move an additional distance in the medium, when the force is no longer being applied at the first location. Both the distance traveled by the object and how long the object is subject to the force depend on a property of the object. At least one of the times and locations of applying the force is selected based on the property of the object.
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