document.write( "Question 430208: A projectile is thrown upward so that its distance above the ground after t seconds is h=-15t(squared)+390t. After how many seconds does it reach its maximum height? \n" ); document.write( "

Algebra.Com's Answer #298766 by poliphob3.14(115) $\"\"$ $\"About$

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Solution:The projectile reach its maximum height when its velocity become zero.\r
\n" ); document.write( "\n" ); document.write( "The velocity is: $\"+d%28h%29%2Fdt=v=-30t%2B390\"$ , for v=0\r
\n" ); document.write( "\n" ); document.write( " $\"-30t%2B390=0\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"30t=390\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"t=33\"$ second.\r
\n" ); document.write( "\n" ); document.write( "Answer: After 33 s the projectile reach maximum height.\r
\n" ); document.write( "\n" ); document.write( "Done. \n" ); document.write( "

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