Final answer:
Kennedy applied the rhetorical strategy of analogy in his Rice University address, comparing the pioneering spirit of American forebears to the attitude needed for space exploration.
Step-by-step explanation:
In the excerpt from his address at Rice University, Kennedy is using the rhetorical strategy of analogy. He compares the past actions of those who built the United States through their relentless effort and refusal to wait or rest, to the future challenges of space exploration. This use of comparison serves to inspire a similar spirit of determination and progress in facing the new frontier of space.