document.write( "Question 770139: A ball is dropped from a bridge 150 feet above a river. How long will it take for the ball to hit the surface of the water? \n" ); document.write( "
Algebra.Com's Answer #469298 by Edwin McCravy(20055)\"\" \"About 
You can put this solution on YOUR website!
\r\n" );
document.write( "The formula is\r\n" );
document.write( "\r\n" );
document.write( "h = ho - 16t²\r\n" );
document.write( "\r\n" );
document.write( "h = the variable height the ball is above the river at variable time t.\r\n" );
document.write( "\r\n" );
document.write( "ho = the height above the river that the ball is dropped = 150 ft.\r\n" );
document.write( "\r\n" );
document.write( "When the ball hits the surface of the water is is 0 ft above the river.\r\n" );
document.write( "\r\n" );
document.write( "So we set h = 0 and ho = 150 and solve for t\r\n" );
document.write( "\r\n" );
document.write( "0 = 150 - 16t²\r\n" );
document.write( "\r\n" );
document.write( "16t² = 150\r\n" );
document.write( "\r\n" );
document.write( "  t² = \"150%2F16\"\r\n" );
document.write( "\r\n" );
document.write( "Take the square root of both sides, (we don't need ± because\r\n" );
document.write( "time is never negative.\r\n" );
document.write( "\r\n" );
document.write( "   t = \"sqrt%28150%2F16%29\"\r\n" );
document.write( "\r\n" );
document.write( "   t = \"sqrt%28150%29%2F4\"\r\n" );
document.write( "\r\n" );
document.write( "   t = \"sqrt%2825%2A6%29%2F4\"\r\n" );
document.write( "  \r\n" );
document.write( "   t = \"5sqrt%286%29%2F4\" or 3.06 seconds approximately.\r\n" );
document.write( "\r\n" );
document.write( "Edwin
\n" ); document.write( "
\n" );