document.write( "Question 861543: When a body is projected vertically upwards with the velocity v=7m/s, the height s reached by the body after time t secs is given in meters by the formula S=7t-4.9t^2. Find the greatest height to which the body will rise and the time taken.
\n" ); document.write( "Please help me, I will really appreciate it. Thanks \n" ); document.write( "

Algebra.Com's Answer #519130 by rothauserc(4718) $\"\"$ $\"About$

You can put this solution on YOUR website!
S=7t-4.9t^2
\n" ); document.write( "The precalculus solution is to graph the equation
\n" ); document.write( " $\"+graph%28+300%2C+200%2C+-4%2C+4%2C+-3%2C+3%2C+-4.9x%5E2+%2B7x%29+\"$
\n" ); document.write( "from the graph we see t = 0.7 seconds and the max height is 2.5 meters
\n" ); document.write( "the calculus solution is to take the first derivative and set it = 0
\n" ); document.write( "S' = 7 - 9.8t
\n" ); document.write( "7 - 9.8t = 0
\n" ); document.write( "9.8t = 7
\n" ); document.write( "t = 7/9.8 = 0.71
\n" ); document.write( "then substitute for t in orignal equation
\n" ); document.write( "S = 7*(0.71) - 4.9*(0.71)^2
\n" ); document.write( "S = 2.5
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