m trying to figure out how long the water from a fountain stays in the air. The equation for the fountain is y=-16x^2+68.5x+0 (68.5 is velocity and 0 is starting height) I think that gives me x intercepts of (0,4.2812,0) Now how do i see how long it stays in the air?

Question

amistre64 · Answer

so what does the variable x represent?

anonymous · Answer

time?

anonymous · Answer

I'm not sure. I cant figure out how to do this . It says to substiute the velocity of 68.5 and the starting height into this equation. y=-16x^2+vx+s. I also know that the height of the fountain reaches 560 feet. What am I missing

anonymous · Answer

Starting height is 0(s)

amistre64 · Answer

you are missing what the variable they are using is actually measuring ...

amistre64 · Answer

y = position with respect to time; the variable they use represents the time that has passed.

amistre64 · Answer

if you know the x intercepts; then you know the time that the height of the water starts (0) and the time it hits the ground again (the other intercept)

anonymous · Answer

hmm, It says to graph equation and get x intercepts rounding to 5 . I did that and got (0, 4.2812,0). Then it says ,"how long does this mean the water from your fountain will remain in the air." I don't get it. I'm sorry. so what do I do now to get that answer.

anonymous · Answer

so , is it 4.3 seconds?

amistre64 · Answer

what does this mean:   (0, 4.2812,0)  ?

anonymous · Answer

thats what the x intercepts are , I think

amistre64 · Answer

are there 3 x intercepts?

anonymous · Answer

I used the online graphing tool and it gave me that answer

amistre64 · Answer

try using wolframalpha.com then ....

amistre64 · Answer

http://www.wolframalpha.com/input/?i=-16x%5E2%2B68.5x%2B0

amistre64 · Answer

but yes, 0 is the time it starts, and 4.28 is the time it lands

anonymous · Answer

"68.5 is velocity and 0 is starting height"

are we projecting it at an angle or vertically upwards?

anonymous · Answer

@amistre64 ok. Thanks for the help. I really appreciate it.

anonymous · Answer

vertically upwards

anonymous · Answer

ah ok sorry, i thought x meant horizontal displacement. seems you have it sorted

anonymous · Answer

Thank you though for answering

amistre64 · Answer

good luck

anonymous · Answer

thanks , I'll need it!