Question 71221:   I have been trying to figure this out for two days and I am stuck. I have been through my text book and web site but I just don;t get it, can you help? 
the question is not from a text book 
thnks
 
 
 Suppose a baseball is shot up from the ground straight up with an initial velocity of 64 feet per second. A function can be created by expressing distance above the ground, s, as a function of time, t. This function is s = -16t2 + v0t + s0 
 
·         16 represents 1/2g, the gravitational pull due to gravity (measured in feet per second2). 
 
·         v0 is the initial velocity (how hard do you throw the object, measured in feet per second).
 
·         s0 is the initial distance above ground (in feet). If you are standing on the ground, then s0 = 0.
 
a)   What is the function that describes this problem? 
Answer: 
 
 
 
 
 
 
b)   The ball will be how high above the ground after 1 second? 
Answer:           
 
Show work in this space.        
 
 
 
 
 
 
c)   How long will it take to hit the ground? 
Answer:           
 
Show work in this space. 
 
 
 
 
 
 
d)   What is the maximum height of the ball?  What time will the maximum height be attained? 
Answer:
 
 
Show work in this space.        
 
 
 
 Answer by stanbon(75887)      (Show Source): 
You can  put this solution on YOUR website! Suppose a baseball is shot up from the ground straight up with an initial velocity of 64 feet per second. A function can be created by expressing distance above the ground, s, as a function of time, t. This function is  
s = -16t2 + v0t + s0  
· 16 represents 1/2g, the gravitational pull due to gravity (measured in feet per second2).  
· v0 is the initial velocity (how hard do you throw the object, measured in feet per second).  
· s0 is the initial distance above ground (in feet). If you are standing on the ground, then s0 = 0.  
a) What is the function that describes this problem? 
Answer:  
s(t) = -16t^2 + 64t + 0 
-------------
 
b) The ball will be how high above the ground after 1 second? 
Answer:  
Show work in this space.  
s(1) = -16(1)^2 + 64(t) 
s(1) = -16 + 64 
s(1) = 48 ft. 
-----------------------
 
c) How long will it take to hit the ground? 
Answer:  
Show work in this space. 
Its height will be zero when it hits the ground. 
So 0 = -16t^2 + 64t 
t(-16t+64)=0 
t= 0 or -16t+64=0 
t=0 seconds or t= 4seconds 
The height will be zero at the start and after 4 seconds. 
 ----------------------------
 
 
d) What is the maximum height of the ball? What time will the maximum height be attained? 
Answer: 
 
Show work in this space. 
s(t) = -16t^2 + 64t +0 
This is a quadratic with a=-16, b=64, c=0 
The high point is at t=-b/2a = -(64)/(-32) = 2 seconds 
It reaches its highest point after 2 seconds. 
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Cheers, 
Stan H.
 
 
 
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