document.write( "Question 555141: The stopping distance D of a car after the brakes are applied varies directly as the square of the speed R. If a car traveling 40mph can stop in 90ft, how many feet will it take for the same car to stop traveling 90 mph?
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\n" ); document.write( "\n" ); document.write( "Please help with this word problem. Thank you.
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Algebra.Com's Answer #361727 by ankor@dixie-net.com(22740)\"\" \"About 
You can put this solution on YOUR website!
The stopping distance D of a car after the brakes are applied varies directly as the square of the speed R.
\n" ); document.write( " If a car traveling 40mph can stop in 90ft, how many feet will it take for the same car to stop traveling 90 mph?
\n" ); document.write( ":
\n" ); document.write( "Find the constant of variation, k:
\n" ); document.write( "k*R^2 = D
\n" ); document.write( "R = 40, D = 90
\n" ); document.write( "k*40^2 = 90
\n" ); document.write( "1600k = 90
\n" ); document.write( "k = \"90%2F1600\"
\n" ); document.write( "k = .05625
\n" ); document.write( ":
\n" ); document.write( "D = .05625R^2; the equation
\n" ); document.write( "At 90 mph
\n" ); document.write( "D = .05625*90^2
\n" ); document.write( "D = 455.625 ft at 90 mph\r
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