SOLUTION: a ball thrown verticaly into the air such that its height can be described by the following function h(t)=16t2 +48t+6 where t is the time (in seconds) since the ball was thrown an

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Question 1199164: a ball thrown verticaly into the air such that its height can be described by the following function h(t)=16t2 +48t+6 where t is the time (in seconds) since the ball was thrown and h (t) is the heigth of the ball (in feet) above the ground. a)at what time does the ball reach its maximun height seconds b)what is the maximum height feet c) when does the ball hit the ground (round to the nearest hundreth) seconds. d) what is h (2) h(2)= e) interpret what the ordered pair (3,6)means in the context of the problem. use a complete sentence in your answer.
Found 2 solutions by ikleyn, math_tutor2020:
Answer by ikleyn(52787)   (Show Source): You can put this solution on YOUR website!
.
a ball thrown verticaly into the air such that its height can be described by the following function h(t)=16t2 +48t+6
where t is the time (in seconds) since the ball was thrown and h (t) is the heigth of the ball (in feet) above the ground.
a) at what time does the ball reach its maximun height seconds
b) what is the maximum height feet
c) when does the ball hit the ground (round to the nearest hundreth) seconds.
d) what is h (2) h(2)=
e) interpret what the ordered pair (3,6)means in the context of the problem. use a complete sentence in your answer.
~~~~~~~~~~~~~~~~~~


As it is written in your post,  this formula for the height does not work.


            Introduction written specially for beginners who don't know the subject AT ALL



The formula in your post is written incorrectly.   FATALLY  INCORRECTLY,  it is what I want to say.

I observed it many times in this forum that the students / (the visitors)  write this formula incorrectly.
because they do not understand the meaning of its terms.

So I prepared this text below as a standard introduction to the subject for such students / visitors.

Be calm,  you are in good hands,  and read my post to the very end.


---------------

If you have the formula for a height given to you as a function of time in the form


    h(t) = -at^2 + bt + c,    (1)


where "a", "b" and "c" are real numbers, a > 0, then in this formula



    (a)  the initial height is equal to the coefficient "c" value;


    (b)  the initial velocity is the coefficient  "b" in the formula;


    (c)  the coefficient "a" value is half of the gravity acceleration.

         For the Earth conditions, the gravity acceleration is g = 9.81 m/s^2, or 32 ft/s^2.


         THEREFORE, if you use meters for height, you should use the approximate value of g = 10 m/s^2.

         So, in this case  a =  = 5  (the numerical value).


         ALTERNATIVELY, if you use feet for height, you should use the approximate value of g = 32 ft/s^2.

         So, in this case  a =  = 16  (the numerical value).



    (d)  To find the height at the time moment "t", simply substitute the value of "t" into the formula (1) and calculate.


    (e)  To find the time "t" when the height has a given value h = , substitute  h =  into equation (1)

         and solve equation  


             h(t) = -at^2 + bt + c = .    (2)



    (f)  To find the time when the height is maximal, use the formula


              = .      (3)



    (g)  To find the maximal height, substitute the time value  t=   of the formula (3)  into the formula (1).

That's all you need to know.


        After my explanations,  you can solve the problem on  YOUR  OWN  now,
        but for it,  you should have your governing equation written correctly.


---------------


To see numerous examples of solved problems,  look into the lessons
    - Problem on a projectile moving vertically up and down
    - Problem on an arrow shot vertically upward
    - Problem on a ball thrown vertically up from the top of a tower
    - Problem on a toy rocket launched vertically up from a tall platform
in this site.

Consider these lessons as your textbook,  handbook,  tutorials and  (free of charge)  home teacher.
Read them attentively and learn how to solve this type of problems once and for all.

Also,  you have this free of charge online textbook in ALGEBRA-I in this site
    - ALGEBRA-I - YOUR ONLINE TEXTBOOK.

The referred lessons are the part of this textbook under the topic "Projectiles launched/thrown and moving vertically up and dawn".


Save the link to this online textbook together with its description

Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson

to your archive and use it when it is needed.


================


If this introduction is helpful to you,  I will be happy.

If it is not enough for you to solve the problem,  come again,
but with one indispensable condition:  your equation  MUST  be written correctly   (showing your understanding).


Come again,  if you need.



Answer by math_tutor2020(3817)   (Show Source): You can put this solution on YOUR website!

I have a feeling the function should be
h(t) = -16t^2 + 48t + 6
where the 16 is negative up front.

--------------------------------------------------

Part (a)

I'll use x in place of t, and y in place of h(t).

The equation turns into
y = -16x^2 + 48x + 6
Compare this to
y = ax^2 + bx + c
to find that
a = -16
b = 48
c = 6

We'll use the first two values to compute the following:
h = -b/(2a)
h = -48/(2*(-16))
h = 1.5
This is the x coordinate of the vertex (h,k).


Answer: The ball reaches max height at 1.5 seconds

--------------------------------------------------

Part (b)

Use the previous result to find the y coordinate of the vertex.
y = -16x^2 + 48x + 6
y = -16(1.5)^2 + 48(1.5) + 6
y = 42
The vertex is located at (h,k) = (1.5, 42).
This represents the highest point of this parabola.

Answer: The max height of the ball is 42 feet

--------------------------------------------------

Part (c)

Replace y with 0 and solve for x.
y = -16x^2 + 48x + 6
0 = -16x^2 + 48x + 6
-16x^2 + 48x + 6 = 0
-2(8x^2 - 24x - 3) = 0
8x^2 - 24x - 3 = 0

We plug these values into the quadratic formula
a = 8
b = -24
c = -3








or

or

or
The steps in your homework do not to be as verbose as what I've described above.
You can skip a few steps.
The decimal values are approximate.
Ignore the negative x solution because a negative time value makes no sense.

Answer: The ball hits the ground at approximately 3.12 seconds

--------------------------------------------------

I'll let the student handle parts (d) and (e).

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