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Question

A model rocket is launched with an intial upward velocity of 105 ft/s. The rocket height h (in feet) after t seconds is given by the following.

 

h=195t-16t^2

 

find all values of t for which the rockets height is 87 feet 

 

round your answer(s) to the nearest hundredth. 

 

 

 

 

Answer 1

h = 87 = 195t - 16t^2

16t^2 - 195t + 87 = 0

t = about .5 seconds and 11.7 seconds when height = 87 feet

Unless you mean vo = 105 ft/sec, then

16t^2 -105t + 87 = 0 and

t = about 1 second and 5.6 seconds