Assertion: roller coaster | /r/HasProperty | pulled to the top of the first big hill
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Source sentences:
text: This is extremely important in roller coasters, because engineers and architects must make certain that a roller coaster car will be able to go down a big slope, and maintain enough speed to be able to climb the next hill, and have enough speed to complete the entire track (since once a roller coaster is pulled to the top of the first big hill, only the forces of gravity and friction [not electricity] are at work).