Question 1166888
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<pre>

To calculate the height of the object 7 seconds after it leaves the ground,

simply substitute t= 7 into the given formula for h(t) and calculate.

You will get then


     h(7) = -16*7^2 + 32*7 + 5 = -555.


It means that at t= 7 seconds the ball will be much lower than the ground surface,
which means that at t= 7 the formula DOES NOT work, actually.


At the time t=7 seconds the ball will be,  gm-m-m,  on the ground surface or somewhere else,
but the given formula just does not work for this time moment.



To answer the second question, you should solve this equation

    h(t) = 0 = -16*t^2 + 32t + 5 = 0.


I leave it to you to solve it - it is a simple exercise.



The last notice is that the formula for h(t) works only till that moment,
when the ball will reach the ground.
</pre>

Is everything clear to you from my explanation ?


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In this site, &nbsp;there is a bunch of lessons on a projectile thrown/shot/launched vertically up

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/travel/Problem-on-a-projectile-moving-vertically.lesson>Problem on a projectile moving vertically up and down</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/travel/Problem-on-projectile-shooted-vertically-upward.lesson>Problem on an arrow shot vertically upward</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/travel/Typical-problems-on-an-projectile-moving-vertically-up-and-down.lesson>Problem on a ball thrown vertically up from the top of a tower</A> 

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/travel/Problem-on-a-toy-rocket-launched-vertically-up--from-the-top-of-a-platform.lesson>Problem on a toy rocket launched vertically up from a tall platform</A>


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


Also, &nbsp;you have this free of charge online textbook in ALGEBRA-I in this site

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson>ALGEBRA-I - YOUR ONLINE TEXTBOOK</A>.


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



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.



Happy learning (!)