An object is thrown downward with an initial velocity of 3 feet per second. The relationship between the distance s it travels and time t is given by s=3t+16t^2 . How long does it take the object to fall 70 feet?

1 Answer
Al E.
Feb 7, 2018

Consider,

#x = 3t + 16t^2# where #x=70m# in this case.

Hence,

#70 = 3t + 16t^2#
#=> -16t^2 - 3t + 70 = 0#
#therefore t = 2s, -2.19s#

The only physically significant answer here is #2s#.

To be sure, you are given a relationship between distance and time, this doesn't include velocity or acceleration. Thus, you can merely solve for the time through the given relationship.

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