1ๆฌใฎๆฃใซ่คๆฐใฎๅใใฏใใใใฆใใพใใๅใฎใขใผใกใณใใฏใๅ่ปขใ่ตทใใ่ฝๅใใฎๅคงใใใงใๅ \(F\) ใจๆฏ็นใใใฎใใงใฎ้ทใ \(l\) ใฎ็ฉใง่กจใใใพใใๅๆ่จๅใใๆญฃใๆ่จๅใใ่ฒ ใจๆฑบใใฆใใใใใใฎใขใผใกใณใใ็ฌฆๅทไปใใง่ถณใใฆใใใพใใๆ็ต็ใซๆญฃใชใๅๆ่จๅใใ่ฒ ใชใๆ่จๅใใซๆฃใๅใใใจใใพใใ
ใคใกใผใธใฏใ็ถฑๅผใใใ่คๆฐใฎใใผใ ใใใใใใฎๅผทใใงๅผใฃๅผตใใๅ่จใฎๅผใใฎๅผทใใจๅใใๆฑบใใ่จ็ฎใจๅใใงใใ
ๅๅใๆฏ็นใพใใใซใคใใใขใผใกใณใใฎไปฃๆฐๅใ็ฌฆๅทใฏๅๆ่จๅใใๆญฃใๆ่จๅใใ่ฒ ใจใใฆใใในใฆใฎๅใซใคใใฆ \(N_i = \pm F_i \cdot l_i\) ใ่ถณใๅใใใใ
ใใงใฎ้ทใใฏใๆฏ็นใใๅใฎไฝ็จ็ทใธใฎๅ็ด่ท้ขใใๅใๆใใซๅ ใใฃใฆใใใจใใฏไฝ็จ็ทใๅปถ้ทใใฆใๆฏ็นใใใฎๅ็ด่ท้ขใๆธฌใใ็ฌฆๅทใๅใ้ใใใจใขใผใกใณใใฎๅ่จใ็้ใซใชใใฎใงใๅฟ ใๅ่ปขใฎๅใใใใงใใฏใใใใ