Question

9. An object is fired straight up from the top of a 200-foot tower at a velocity of 80 feet per second. The height, h(t) of the object t seconds after firing is given by h(t) = -16t^2 + 80t + 200.
A. Find the maximum height reached by the object and the time that the height is reached.
B. Interpret the meaning of the y-intercept in the context of this problem.

Answer 1

If you were to graph it on your calculator (or wolfram) the answer to A. is the y value at the maximum point.

Answer 2

y-intercept you have to think about it. that is at time 0. Right?! Because the y-intercept is when x=0. So at time 0 what is the height? Hint: it is the initial height

Answer 3

Is it 299.95473???? ????

Answer 4

idk I didn't do it

Answer 5

that number is y, but I don't think it's the y-intercept

Answer 6

\[h(t) = -16t^2 + 80t + 200\]\[h'(t) = -32t + 80\]\[0 = -32t + 80\]\[32t=80\]\[t=2.5\]\[h(t) = -16(2.5)^2 + 80(2.5) + 200\]\[h(t)=300\]

Answer 7

300 is the answer to A

Answer 8

reread my initial post for B

Answer 9

It says it need the height and the time

Answer 10

hate to say it but 300 is an exact answer. I don't know how wolfram got its 299.whatever

The time is the x value.

Answer 11

wolframalpha got 300; t = \[\frac{ 5 }{ 2 }\]

Answer 12

which is 2.5, which is what I got. See how quick calculus is?!

Answer 13

I want to make sure you are understanding. Do you know why time is the x-value and height is the y value?

Answer 14

explain it real quick

Answer 15

\[h(t) = -16t^2 + 80t + 200\]h stands for height in this problem. and h depends on t. That's what h(t) means. You say it as "h of t". Means height changes as t changes. t stands for time. say we had our finger on the x-axis and moved it to the right. we are increasing the time which is increasing the height on the y-axis.

did this help

Answer 16

I should have probably said changing the height as time changes, because the height goes up then back down

Answer 17

okay I get it now partially

Answer 18

just remember that h(t) or f(x) or anything of anything is usually always referring to the y-axis. and the of something or t or x is the x-axis

Answer 19

I am pretty sure we'll get more in to that later in the year maybe

Answer 20

definitely

Answer 21

Good luck

Answer 22

are you sure we'll learn it in Algebra2

Answer 23

definitely

Answer 24

What was your initial post for B

Answer 25

the initial height is the height of the beginning. That is at time zero

Answer 26

building not beginning

Answer 27

A is 300 - maximum height and 5/2 - t(time)
B was what???

Answer 28

height of the building.

Answer 29

so is B the height of the building

Answer 30

You know what @ChmE

Answer 31

Thanks a whole lot man I hope you can help me out later sometime! :D