politja simple

m_{1}·d_{tt}^{2}[y_{1}(t)] = ( q_{1}·g+(-1)·T )
m_{2}·d_{tt}^{2}[y_{2}(t)] = ( (-1)·q_{2}·g+T )


(m_{1}+m_{2})·d_{tt}^{2}[y_{1}(t)] = ( q_{1}+(-1)q_{2} )·g


T = ( (m_{2}·q_{1}+m_{1}·q_{2})/(m_{1}+m_{2}) )·g


(-T) = m_{1}·( ( q_{1}+(-1)q_{2} )/(m_{1}+m_{2}) )·g+...
...( (-1)·((m_{1}+m_{2})·q_{1})/(m_{1}+m_{2}) )·g


T = m_{2}·( ( q_{1}+(-1)q_{2} )/(m_{1}+m_{2}) )·g+...
...( ((m_{1}+m_{2})·q_{2})/(m_{1}+m_{2}) )·g


politja simple sense càrrega  estirada per una força constant.
m·d_{tt}^{2}[y(t)] = ( q_{1}·g+q_{2}·g )+(-1)·F


politja simple sense càrrega penjada de una molla.
m·d_{tt}^{2}[y(t)] = ( q_{1}·g+q_{2}·g )+(-1)·k·y(t)


politja simple sense càrrega estirada per una força dependent del temps.
m·d_{tt}^{2}[y(t)] = ( q_{1}·g+q_{2}·g )+(-1)·F(t)