SOLUTION: if a projectile is fired straight upward from the ground with an initial speed of 40 ft per second,neglecting air resistance,its height s (in feet) above t seconds after projection

Question 1123040: if a projectile is fired straight upward from the ground with an initial speed of 40 ft per second,neglecting air resistance,its height s (in feet) above t seconds after projection is given by s=-16t^2+40t. which equation should be used to determine the time at which the height of the projectile reaches 40ft?
Answer by ikleyn(52790) (Show Source): You can put this solution on YOUR website!
.

The equation you are asking for is


s(t) = 40,   or


-16t^2 + 40t = 40.


But the problem is that this equation has NO real solutions, and maximal height of the projectile is only 25 ft, so it will NEVER reach 40 ft height.






Plot s(t) =

Who gave you this fake problem ?

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

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.

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