Question

The height of a projectile in feet at time t is determined by the
equation h = -16t2 + 112t + 128. At what time will the projec-
tile be 0 feet high?
(1) 5 seconds
(3) 7 seconds
(2) 6 seconds
(4) 8 seconds​

Answer 1

Option 4. 8 sec is the correct answer

Step-by-step explanation:

Given

$h=-16t^2+112t+128$

To find the time at which the height will be zero feet,we will put h = 0

$-16t^2+112t+128 = 0\\-16(t^2-7t-8) = 0\\t^2-8t+t-8=0\\t(t-8)+1(t-8)=0\\(t+1)(t-8)=0\\t+1 = 0 => t=-1\\t-8=0 => t =8$

As the value of time cannot be negative, we will only consider the positive value:

Option 4. 8 sec is the correct answer

Keywords: Physics, Time

Learn more about time at:

• brainly.com/question/11007026
• brainly.com/question/11207748

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