document.write( "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? \n" ); document.write( "

Algebra.Com's Answer #739254 by ikleyn(52790) $\"\"$ $\"About$

You can put this solution on YOUR website!
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document.write( "The equation you are asking for is\r\n" );
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document.write( "s(t) = 40,   or\r\n" );
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document.write( "-16t^2 + 40t = 40.\r\n" );
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document.write( "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.\r\n" );
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document.write( "Plot s(t) =  \r\n" );
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\n" ); document.write( "\n" ); document.write( "Who gave you this fake problem ?\r
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\n" ); document.write( "\n" ); document.write( "In this site, there is a bunch of lessons on a projectile thrown/shot/launched vertically up\r
\n" ); document.write( "\n" ); document.write( "    - Problem on a projectile moving vertically up and down\r
\n" ); document.write( "\n" ); document.write( "    - Problem on an arrow shot vertically upward\r
\n" ); document.write( "\n" ); document.write( "    - Problem on a ball thrown vertically up from the top of a tower \r
\n" ); document.write( "\n" ); document.write( "    - Problem on a toy rocket launched vertically up from a tall platform\r
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\n" ); document.write( "\n" ); document.write( "Also, you have this free of charge online textbook in ALGEBRA-I in this site\r
\n" ); document.write( "\n" ); document.write( "    - ALGEBRA-I - YOUR ONLINE TEXTBOOK.\r
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\n" ); document.write( "\n" ); document.write( "The referred lessons are the part of this textbook under the topic \"Projectiles launched/thrown and moving vertically up and dawn\".\r
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\n" ); document.write( "\n" ); document.write( "Save the link to this online textbook together with its description\r
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\n" ); document.write( "\n" ); document.write( "Free of charge online textbook in ALGEBRA-I
\n" ); document.write( "https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson\r
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\n" ); document.write( "\n" ); document.write( "to your archive and use it when it is needed.\r
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