English Deutsch Français Italiano Español Português 繁體中文 Bahasa Indonesia Tiếng Việt ภาษาไทย
All categories

how many seconds will a ball take to reach a height of 200 ft?

h = -16x^2 + 28 x +144

h = height and x = time ( second )

I know that I have to plug in 200 into h and solve for x
but I just can't get an answer... can anyone help me with this?

2007-11-26 11:45:01 · 4 answers · asked by melong_91 1 in Science & Mathematics Mathematics

4 answers

200 = -16x^2 + 28x + 144

16x^2 - 28x + 56 = 0

Hmmm. . . I put this into the quadratic formula and come up with complex answers. I got -2800 under the radical. I think, perhaps, the ball will not reach a height of 200 feet.
Yeah, I just determined the vertex and it reaches a maximum height of 156.25 at 7/8 sec. That's why this isn't working.

2007-11-26 11:52:12 · answer #1 · answered by Marley K 7 · 0 0

200 = -16t² + 28t + 144
0 = -16t² + 28t - 56
0 = 4t² - 7t + 14
using quadratic formula ...
t = [7 ± √(49 - 224)] / 8

see that big √negative? there's no real solution here. In the original equation, the ball is already at 144 ft, needing only 56 to reach 200. The 28t term gives it 28 ft/s upward velocity, which gets it to 200 ft in 2 sec, but in 2 sec the -16t² term will pull it down 16(2)² = 64 ft.

2007-11-26 12:06:42 · answer #2 · answered by Philo 7 · 0 0

h = rx + 16x{2-expontent}
so teh height is 200
200 = rx + 16x{2}
but u didn't say teh rate.

in yours:
h = -16x{2} + 28x + 144
not sure how you got this, but i think u could try this
16x{2} -28x - 144 = 0
4(4x{2} - 7x - 36) = 0
then factor and find x
like i said, i'm still not sure how u got here

but if u say the rate, i'll try to come back and telll u

2007-11-26 12:02:05 · answer #3 · answered by Anonymous · 0 0

the ball can't reach 200 ft

2007-11-26 11:50:31 · answer #4 · answered by Anonymous · 0 0

fedest.com, questions and answers