SOLUTION: If an object is thrown upward with an initial velocity of 80 ft/sec, its height after t sec is given by h = 80t - 16t^2. Find the number of seconds before the object hits the groun

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: If an object is thrown upward with an initial velocity of 80 ft/sec, its height after t sec is given by h = 80t - 16t^2. Find the number of seconds before the object hits the groun      Log On


   

Question 168270This question is from textbook Introductory Algebra
: If an object is thrown upward with an initial velocity of 80 ft/sec, its height after t sec is given by h = 80t - 16t^2. Find the number of seconds before the object hits the ground. This question is from textbook Introductory Algebra

Answer by HyperBrain(694) About Me  (Show Source):
You can put this solution on YOUR website!
By the moment that the object hits the ground, h=0.
Thus, substituting,
0=80t-16t2
factor out t
t(80-16t)=0
t=0 or 80-16t=0
16t=80
t=5
SO, it's 0 or 5 seconds.
HOwever, at t=0, the object is not falling but was about to go up with the initial velocity of 80 ft/sec
So, the answer is that t=5.

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