Problema Solution
A projectile that is fired vertically into the air with an initial velocity of 120ft per second can be modelled by the equation s=120 t=16t².In the equation, s is the distance in feet of the projectile above the ground after t seconds. How long will it take of projectile to reach 216ft?
Answer provided by our tutors
s=120t-16t^2
We need to find t such that s = 216 ft, that is, solve the following quadratic equation:
120t-16t^2 = 216
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click here to see the equation solved for t
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t1 = 3 s
t2 = 4.5 s
The projectile will reach 216 ft for the first time (on the way up) after 3 seconds, and second time (on the way down) after 4.5 seconds.