Skip to main content

Half Circle

  • circle half 4circle half 8Half of the interior of a circle having a straight chord and an arc.
  • Center of a circle having all points on the line circumference are at equal distance from the center point.
  • A half circle is a structural shape used in construction.

 

Arc Length of a Half Circle formula

\( l \;=\;  \dfrac{ 2 \cdot \pi \cdot r  }{ 2 } \) 
Symbol English Metric
\(\large{ l }\) = length \( in \) \( mm \)
\(\large{ \pi }\) = Pi \(3.141 592 653 ...\) \(3.141 592 653 ...\)
\(\large{ r }\) = radius \( in \) \( mm \)

   

Area of a Half Circle formula

\( A_{area} \;=\; \dfrac{ \pi \cdot r^2 }{ 2 }\) 
Symbol English Metric
\(\large{ A }\) = area \( in^2 \) \( mm^2 \)
\(\large{ \pi }\) = Pi \(3.141 592 653 ...\) \(3.141 592 653 ...\)
\(\large{ r }\) = radius \( in \) \( mm \)

 

Perimeter of a Half Circle formula

\( P \;=\;   \dfrac{ 2 \cdot \pi \cdot r}{ 2 } + (2 \cdot r)   \) 
Symbol English Metric
\(\large{ P }\) = perimeter \( in \) \( mm \)
\(\large{ \pi }\) = Pi \(3.141 592 653 ...\) \(3.141 592 653 ...\)
\(\large{ r }\) = radius \( in \) \( mm \)

   

Radius of a Half Circle formula

\( r \;=\; \sqrt{  \dfrac{ 2 \cdot A_{area} }{ \pi }  } \) 
Symbol English Metric
\(\large{ A }\) = area \( in^2 \) \( mm^2 \)
\(\large{ \pi }\) = Pi \(3.141 592 653 ...\) \(3.141 592 653 ...\)
\(\large{ r }\) = radius \( in \) \( mm \)

   

Distance from Centroid of a Half Circle formulas

\( C_x \;=\; 0   \)

\( C_y \;=\;  \dfrac{ 4 \cdot r }{ 3 \cdot \pi } \) 

Symbol English Metric
\(\large{ C_x, C_y }\) = distance from centroid \( in \) \( mm \)
\(\large{ \pi }\) = Pi \(3.141 592 653 ...\) \(3.141 592 653 ...\)
\(\large{ r }\) = radius \( in \) \( mm \)

   

Elastic Section Modulus of a Half Circle formula

\( S \;=\;  \dfrac{ I_x }{ C_y }\) 
Symbol English Metric
\(\large{ S }\) = elastic section modulus \( in^3 \) \( mm^3 \)
\(\large{ C_x, C_y }\) = distance from centroid \( in \) \( mm \)

 

Polar Moment of Inertia of a Circle formulas

\( J_{z} \;=\;   \left(   \dfrac{ \pi}{ 4 }  -  \dfrac{ 8 }{ 9 \cdot \pi } \right) \cdot  r^4   \) 

\( J_{z1} \;=\;   \dfrac{ \pi \cdot r^4 }{  4 } \) 

Symbol English Metric
\(\large{ J }\) = torsional constant \( in^4 \) \( mm^4 \)
\(\large{ \pi }\) = Pi \(3.141 592 653 ...\) \(3.141 592 653 ...\)
\(\large{ r }\) = radius \( in \) \( mm \)

 

Radius of Gyration of a Half Circle formulas

\( k_{x} \;=\;    r \cdot  \sqrt{   \dfrac{1 }{ 4 }  -  \dfrac{ 16 }{ 9 \cdot \pi^2 }   }  \)

\( k_{y} \;=\;   \dfrac{  r }{  2 }\) 

\( k_{z} \;=\;   r \cdot \sqrt{   \dfrac{ 1 }{ 2 }  -  \dfrac{ 16 }{ 9 \cdot \pi^2 }   }  \)

\( k_{x1} \;=\;   \dfrac{  r }{  2 }\) 

\( k_{y1} \;=\;   \dfrac{ r }{  2 }\) 

\( k_{z1} \;=\;   \dfrac{ \sqrt {2}  }{  2  } \cdot r   \)

Symbol English Metric
\(\large{ k }\) = radius of gyration \( in \) \( mm \)
\(\large{ \pi }\) = Pi \(3.141 592 653 ...\) \(3.141 592 653 ...\)
\(\large{ r }\) = radius \( in \) \( mm \)

 

Second Moment of Area of a Half circle formulas

\( I_{x} \;=\;   \left(  \dfrac{ \pi }{ 8 } - \dfrac{ 8 }{ 9 \cdot \pi }  \right)    \cdot  r^4 \) 

\( I_{y} \;=\; \dfrac{ \pi \cdot r^4}{ 8 }\)

\( I_{x1} \;=\; \dfrac{ \pi \cdot r^4}{ 8 }\)

\( I_{y1} \;=\; \dfrac{ \pi \cdot r^4}{ 8 }\)

Symbol English Metric
\(\large{ I }\) = moment of inertia \( in^4 \) \( mm^4 \) 
\(\large{ \pi }\) = Pi \(3.141 592 653 ...\) \(3.141 592 653 ...\)
\(\large{ r }\) = radius \( in \) \( mm \)

 

Piping Designer Logo 1