SOLUTION: Use the position function s(t) = -16t^2 + v_0t + s_0 v0 = initial velocity, s0 = initial position, t = time to answer the following qu

Algebra ->  Inequalities -> SOLUTION: Use the position function s(t) = -16t^2 + v_0t + s_0 v0 = initial velocity, s0 = initial position, t = time to answer the following qu      Log On


   



Question 994201: Use the position function
s(t) = -16t^2 + v_0t + s_0
v0 = initial velocity,
s0 = initial position,
t = time
to answer the following question.
You throw a ball straight up from a rooftop 170 feet high with an initial velocity of 32 feet per second. During which time period will the ball's height exceed that of the rooftop?
ANSWER: Between ...?? and ...?? seconds.

Found 3 solutions by stanbon, josmiceli, MathLover1:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Use the position function
s(t) = -16t^2 + v_0t + s_0
v0 = initial velocity,
s0 = initial position,
t = time
to answer the following question.
You throw a ball straight up from a rooftop 170 feet high with an initial velocity of 32 feet per second. During which time period will the ball's height exceed that of the rooftop?
===========
-16t^2 + 32t + 170 > 170
-----
-16t^2 + 32t > 0
-----
-16t(t-2) > 0
----
ANSWER: Between 0 and 2 seconds.
----
Cheers,
Stan H.
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Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
You want to know the values of +t+ when
+s%28t%29+%3E+170+
+s%28t%29+=+-16t%5E2+%2B+32t+%2B+170+
When +t+=+0+,
+s%280%29+=+-16%2A0+%2B+32%2A0+%2B+170+
+s%280%29+=+170+
So, +t+=+0+ is the initial time
Now you have to find +t+ when theball is
coming down and is back to the 170 ft level
+s%28t%29+=+170+
+170+=+-16t%5E2+%2B+32t+%2B+170+
+-16t%5E2+%2B+32t+=+0+
+t%2A%28+-16t+%2B+32+%29+=+0+
+16t+=+32+
+t+=+2+
The ball exceeds the height of the rooftop
between 0 and 2 sec
--------------------
Here's a plot of the ball's height and time in sec
+graph%28+400%2C+400%2C+-1%2C+5%2C+-50%2C+250%2C+-16x%5E2+%2B+32x+%2B+170+%29+

Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!
s%28t%29+=+-16t%5E2+%2B+v%5B0%5Dt+%2B+s%5B0%5D
v%5B0%5D+=+initial+_velocity,
s%5B0+%5D=+initial_+position,
t+=+time
given:
s%5B0+%5D=170ft
v%5B0%5D+=32+%28ft%2Fs%29
s%28t%29+%3Es%5B0+%5D
+-16t%5E2+%2B+32t+%2B+170%3E170=>the ball's height exceed that of the rooftop

+-16t%5E2+%2B+32t+%2B+170%3E170
-16t%5E2+%2B32t%3E0
16%28t%5E2+-2t%29=+0
t%5E2+-2t=0

t%28t-2%29=0.

solutions:
t+=+0+
and
t+=+2+


so between t=0 and t=2 at the ball’s height exceed 170ft