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A rock is thrown into the air. The height (in feet) of the rock after t seconds is given by

h = -16t^2 + 64t

.

Answer the following algebraically

.

a)

What is the height reached by the ball after 1 second

?

________________________

b

)

Determine the maximum height the rock attains

________________________

c

)

How long it will take to reach

maximum height.

________________________

d

)

When does the rock hit the ground?

 Oct 31, 2018
 #1
avatar+17338 
+3

When t=1

h= -16(1^2) +64(1) = 48 FT

 

Max = c- b^2/4a  = 0 - (64^2/(4(-16)) = 64 ft

 

t max    64 = -16t^2 +64t        -t^2 +4t -4 = 0       or  t^2 -4t+4 = 0       (t-2)(t-2)     = 0     so t max = 2 sec

 

h= 0

 0 = -16t^2 + 64t

16t = 64

t= 4 sec

 Oct 31, 2018

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