Question

I would just like assistance with the problem, if possible. If a stone is tossed from the top of a 190 meter building, the height of the stone as a function of time is given by h(t)=-9.8t^2-10t +190, where t is in seconds, and height is in meters. After how many seconds will the stone hit the ground? Round to the nearest hundredth's place; include units in your answer.

This is the help I had from two other people, but they ran off, lol. I do not know if it is finished or not. Help me please.
So for the whole problem I have: h(t)=-9.8t^2 -10t +190 -9.8t^2-10t+190=0 t=-3.9 or t=3.9 D=b^2-4ac a

Answer 1

i solved that for u.

Answer 2

hey saifoo

Answer 3

i even remember the method, lol.

Answer 4

Hi Maggie.

Answer 5

show me! i dunno how to solve

Answer 6

so u got dissed by polpak to huh

Answer 7

Again? Didn't we do this like 4 times?

Answer 8

yup;(

Answer 9

its ok ur not the only 1

Answer 10

Maggie, lol.
v wil talk about it sometime later.
If i talk now, my answers will be deleted.

Answer 11

yeah, but everyone left, what is the final answer? isi t just t=-3.9 or t=3.9? or is it d=7548?

Answer 12

k

Answer 13

WRONG.

Answer 14

answers were:

t = 1.02
or
t = 0.

Answer 15

t=3.9

Answer 16

how u get that answer?

Answer 17

SAIFOO YOU ARE WRONG the answer is t = 3.9
u already said it.. set the equation equal to 0

Answer 18

but the height is given.

Answer 19

190 will be cancelled with 190.

Answer 20

the other one said you missed a part of it. this part.
-9.8t^2 -10t +190=0

Answer 21

h(t)=-9.8t^2 -10t +190
h(t) = 0, when the ball touches the ground
so
-9.8t62 - 10t + 190 = 0

Answer 22

190 =-9.8t^2 -10t +190

190 - 190=-9.8t^2 -10t

Answer 23

bahrom where did the 62 come from?

Answer 24

-9.8t^2 -10t

Answer 25

t^2 sorry i forgot to press shift when doing ^

Answer 26

so that is the final answer, this is what I have so far, I will need to come back and give you the answer, just a minute. stay here.

Answer 27

-9.8t^2 - 10t + 190 = 0, you could've guessed that
D = b^2 - 4ac = 100 + 4*9.8*190 = 100 + 7448 = 7548

Answer 28

i didnt used Determinate. :p

Answer 29

t1 = (10 - sqrt(7548))/(2(-9.8))
t2 = (10 + sqrt(7548))/(2(-9.8))
Saifoo first of all it's called discriminant, second of all your method is wrong.

Answer 30

once u settle ur debate, could one of u xplain how u do the problems?

Answer 31

t1 = 3.92240952
t2 = -4.94281768
We disregard the negative sign.

Answer 32

Gandalfwiz aren't u reading my posts?

Answer 33

So for the whole problem I have: h(t)=-9.8t^2 -10t +190 -9.8t^2-10t+190=0 t=-3.9 or t=3.9 D=b^2-4ac a=-9.8 b=-10 c= 190 -10^2-4*-9.8*190 100-4*-9.8 100+39.2*190 100+7448 =7548 Is this right? So what is the final answer t=-3.9 or t=3.9? Or is it 7548?

Answer 34

We disregrad the time with the negative sign since time cannot be negative, therefore the answer is:
t1 = 3.92240952

Answer 35

sorry ! I'm Back! I'm back!

Answer 36

For the 7th and last time, here is the complete, step-by-step solution:
h(t)=-9.8t^2 -10t +190
h(t) = 0, when the ball touches the ground
so
-9.8t^2 - 10t + 190 = 0
D = b^2 - 4ac = 100 + 4*9.8*190 = 100 + 7448 = 7548
t1 = (10 - sqrt(7548))/(2(-9.8))
t2 = -4.94281768
We disregrad the time with the negative sign since time cannot be negative, therefore the answer is:
t1 = 3.92240952

Answer 37

Oh to the nearest hundredth that is:
t = 3.92

Answer 38

How did you come up with your t1 and t2 answers?

Answer 39

Ok, I got it Thank you for your help. See the other ones I posted, I never got the whole problems, just pieces of it.

Answer 40

Nickie do u know how to do quadratics?
ax^2+bx+c=0
D = b^2-4ac
x1 = (-b-sqrt(D))/(2a)
x2 = (-b+sqrt(D))/(2a)

Answer 41

finally..

Answer 42

I was copying the problem. you added the 4 in the diterminate formula. the formula says D=b^2-4ac doesnt that make it all wrong. Nevermind you did it right, just not written down right. Thank you for your help bahrom.