document.write( "Question 374292: When a projectile is fired, the vertical component of its initial velocity is such that its height h metres t seconds after firing is given by $\"h=250t-4.9t%5E2\"$ .\r
\n" ); document.write( "\n" ); document.write( "Determine if the projectile will reach each height.
\n" ); document.write( "a)2.75km
\n" ); document.write( "b)4.0km \n" ); document.write( "

Algebra.Com's Answer #266370 by nerdybill(7384) $\"\"$ $\"About$

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$\"h=250t-4.9t%5E2\"$
\n" ); document.write( "Is a quadratic (parabola) that opens downwards. We can tell because the coefficient associated with the t^2 term is negative. If so, then the vertex defines the hight point.
\n" ); document.write( ".
\n" ); document.write( "Highest point is reached when the time is:
\n" ); document.write( "t = -b/(2a) = -250/(2*(-4.9)) = -250/(-10.8) = 25.51
\n" ); document.write( "Highest point projectile will reach:
\n" ); document.write( " $\"h=250%2825.51%29-4.9%2825.51%29%5E2\"$
\n" ); document.write( " $\"h=3189+\"$ meters
\n" ); document.write( " $\"h=3.189+\"$ kilometers
\n" ); document.write( ".
\n" ); document.write( "So, now we can answer the question:
\n" ); document.write( "a)2.75km (yes)
\n" ); document.write( "b)4.0km (no)\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

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