Final answer:
The literary device used in the sentence is hyperbole. Hyperbole is a figure of speech that involves extreme exaggeration to emphasize a point.
Step-by-step explanation:
The literary device used in the sentence is hyperbole. Hyperbole is a figure of speech that involves extreme exaggeration to emphasize a point. In this sentence, the use of '7th ground' is exaggerated, as there is typically only one ground. This exaggeration is used to emphasize the height from which the object is dropped, creating a sense of dramatic effect.