document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1208118>Question 1208118</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A circular disc of cast iron is 7 ft. in diameter and 1 1/3 in. thick. Determine weight.  \r<BR>\n" );
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document.write( "A plate 1 ft. square and 1 in. thick weighs 37.5 lbs.\r<BR>\n" );
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document.write( "Area of circle:  pi * r^2.\r<BR>\n" );
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document.write( "Not sure how to solve. </SPAN>\n" );
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document.write( "1 ft = 12 in<BR>\n" );
document.write( "7 ft = 7*12 = 84 inches is the diameter, half that (42) is the radius<BR>\n" );
document.write( "1 & 1/3 = 4/3<BR>\n" );
document.write( "Volume of cylinder = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=pi%2Ar%5E2%2Ah ALIGN=MIDDLE  ALT=\"pi%2Ar%5E2%2Ah\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Volume of cylinder = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=pi%2A%2842%29%5E2%2A%284%2F3%29 ALIGN=MIDDLE  ALT=\"pi%2A%2842%29%5E2%2A%284%2F3%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Volume of cylinder = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2352pi ALIGN=MIDDLE  ALT=\"2352pi\"   DISABLED_style= \"max-width:90%; height:auto;\" > cubic inches\r<BR>\n" );
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document.write( "\"A plate 1 ft. square and 1 in. thick weighs 37.5 lbs\"<BR>\n" );
document.write( "means we have a 1 ft by 1 ft by 1 inch rectangular slab of iron<BR>\n" );
document.write( "i.e. we have a 12 inch by 12 inch by 1 inch slab of iron<BR>\n" );
document.write( "The volume of this would be length*width*height = 12*12*1 = 144 cubic inches.<BR>\n" );
document.write( "144 cubic inches of iron weighs 37.5 pounds which will help set up a useful conversion factor. \r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28matrix%281%2C2%2C2352pi%2C%22cubic_inches%22%29%29%28matrix%281%2C2%2C37.5%2C%22pounds%22%29%2Fmatrix%281%2C2%2C144%2C%22cubic_inches%22%29%29 ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28matrix%281%2C2%2C2352pi%2Ccross%28%22cubic_inches%22%29%29%29%28matrix%281%2C2%2C37.5%2C%22pounds%22%29%2Fmatrix%281%2C2%2C144%2Ccross%28%22cubic_inches%22%29%29%29 ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=matrix%281%2C2%2C2352pi%2A%2837.5%2F144%29%2C%22pounds%22%29 ALIGN=MIDDLE  ALT=\"matrix%281%2C2%2C2352pi%2A%2837.5%2F144%29%2C%22pounds%22%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=matrix%281%2C2%2C612.5pi%2C%22pounds%22%29 ALIGN=MIDDLE  ALT=\"matrix%281%2C2%2C612.5pi%2C%22pounds%22%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "This is the exact weight of the circular disc in terms of pi.\r<BR>\n" );
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document.write( "Here are some select approximations of this weight when we try various approximations of pi<BR>\n" );
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document.write( "<tr><TD >rounding precision</TD><TD >pi</TD><TD >weight</TD></tr><tr><TD >2</TD><TD >3.14</TD><TD >1923.25</TD></tr><tr><TD >3</TD><TD >3.142</TD><TD >1924.475</TD></tr><tr><TD >4</TD><TD >3.1416</TD><TD >1924.23</TD></tr><tr><TD >5</TD><TD >3.14159</TD><TD >1924.223875</TD></tr><tr><TD >6</TD><TD >3.141593</TD><TD >1924.2257125</TD></tr><tr><TD >7</TD><TD >3.1415927</TD><TD >1924.22552875</TD></tr><tr><TD >8</TD><TD >3.14159265</TD><TD >1924.225498125</TD></tr><tr><TD >9</TD><TD >3.141592654</TD><TD >1924.225500575</TD></tr><tr><TD >10</TD><TD >3.1415926536</TD><TD >1924.22550033</TD></tr>\n" );
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document.write( "As we use more decimal digits of pi, the weight seems to approach roughly 1924.2255 pounds.<BR>\n" );
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