document.write( "Question 1149884: This is from a test question which I struggled with.\r
\n" ); document.write( "\n" ); document.write( "Use the projectile motion equation: h= -16t^2+V0t+h0\r
\n" ); document.write( "\n" ); document.write( "A baseball is hit from a rooftop 64 feet above the ground with an initial upward velocity of 160 feet per second.\r
\n" ); document.write( "\n" ); document.write( "A. How long after the ball is hit will it be 128 feet above the ground?
\n" ); document.write( "B. How long after the ball is hit will it hit the ground?
\n" ); document.write( "C. What is the height of the ball 2 seconds after it was hit? \n" ); document.write( "

Algebra.Com's Answer #771220 by ikleyn(52839) $\"\"$ $\"About$

You can put this solution on YOUR website!
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document.write( "(A)  To answer (A), you need to substitute  h= 128 into the formula for the current height; \r\n" );
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document.write( "     v0= 160 (initial upward velocity) and h0= 64 (initial height).\r\n" );
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document.write( "     Then you will get the equation\r\n" );
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document.write( "         -16t^2 + 160t + 64 = 128.      (A)\r\n" );
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document.write( "     I will left it to you to solve it on your own.\r\n" );
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document.write( "(B)  To anser (B), you need to solve the equation\r\n" );
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document.write( "                  -16t^2 + 160t + 64 = 0.    (B)\r\n" );
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document.write( "     In this case, the current height is 0 (zero), since the ball hits the ground (which is \"level zero\").\r\n" );
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document.write( "(C)  To answer this question, you need substitute t= 2 (2 seconds) into the given function\r\n" );
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document.write( "         h = -16*2^2 + 160*2 + 128.\r\n" );
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