Tabbiejack 2 years ago If an object is dropped from a height of 144 feet, the function h(t)= -16t^2+144 gives the height of the object after t seconds. When will the object hit the ground? A. 9 s B. 6 s C. 1.5 s D. 3 s

1. whpalmer4

well, solve the equation for h = 0...what positive value of t makes it so?

2. whpalmer4

at t = 0, h(0) = -16(0)^2 + 144 = 144 feet, which is the height from which it is being dropped. at some later t, h(t) = 0, and that's when it hits the ground.

3. whpalmer4

\[h(t) = 0 = -16t^2+144\]\[16t^2=144\]\[t=\]

4. Tabbiejack

so it 9

5. whpalmer4

does 16*9*9 = 144?

6. whpalmer4

always, always check your answers in the original formula to make sure they correctly answer the question.

7. Tabbiejack

no

8. Tabbiejack

its 3

9. passive13

it is 3 gj

10. whpalmer4

16(3)(3) = 144, so that is a reasonable answer. Note that t = -3 also satisfies the equation, but does not satisfy the conditions described in the problem, so it is not a correct solution here.

11. Tabbiejack

ok