\( \DeclareMathOperator{\abs}{abs} \newcommand{\ensuremath}[1]{\mbox{$#1$}} \)

Schwerpunkt und Gewichtskraft

 1 Winkelprofil

 1.1 a) Massen

(%i3) A_1: 200^2; A_2: 800·300; A_ges: A_1+A_2;
\[\tag{A\_ 1}40000\] \[\tag{A\_ 2}240000\] \[\tag{A\_ ges}280000\]
(%i5) m_1: 10·A_1/A_ges;m_2: 10·A_2/A_ges;
\[\tag{m\_ 1}\frac{10}{7}\] \[\tag{m\_ 2}\frac{60}{7}\]

 1.2 b) Schwerpunktlage

(%i9) S_x: 1/10·(m_1·100+m_2·400); float(%); S_y: 1/10·(m_1·400+m_2·150); float(%);
\[\tag{S\_ x}\frac{2500}{7}\] \[\tag{%o7} 357.1428571428572\] \[\tag{S\_ y}\frac{1300}{7}\] \[\tag{%o9} 185.7142857142857\]

 1.3 c) Kräfte

(%i15) F_G: 10·981/100; beta: 20/360·2·%pi; F_H: F_G·sin(beta); float(%); F_N: F_G·cos(beta); float(%);
\[\tag{F\_ G}\frac{981}{10}\] \[\tag{beta}\frac{\ensuremath{\pi} }{9}\] \[\tag{F\_ H}\frac{981 \sin{\left( \frac{\ensuremath{\pi} }{9}\right) }}{10}\] \[\tag{%o13} 33.5521760602481\] \[\tag{F\_ N}\frac{981 \cos{\left( \frac{\ensuremath{\pi} }{9}\right) }}{10}\] \[\tag{%o15} 92.18384609909761\]

 2 Schwerpunkt gebohrter Quader

 2.1 a) Massen

(%i18) A_1: %pi·80^2; A_2: 400·250; A_ges: A_2A_1;
\[\tag{A\_ 1}6400 \ensuremath{\pi} \] \[\tag{A\_ 2}100000\] \[\tag{A\_ ges}100000-6400 \ensuremath{\pi} \]
(%i20) m_1:10·A_1/(A_2A_1); float(%);
\[\tag{m\_ 1}\frac{64000 \ensuremath{\pi} }{100000-6400 \ensuremath{\pi} }\] \[\tag{%o20} 2.51661470815755\]
(%i22) m_2:10·A_2/(A_2A_1); float(%);
\[\tag{m\_ 2}\frac{1000000}{100000-6400 \ensuremath{\pi} }\] \[\tag{%o22} 12.51661470815755\]

 2.2 b) Schwerpunktlage

(%i24) S_x: 1/10·(m_2·200m_1·100); float(%);
\[\tag{S\_ x}\frac{\frac{200000000}{100000-6400 \ensuremath{\pi} }-\frac{6400000 \ensuremath{\pi} }{100000-6400 \ensuremath{\pi} }}{10}\] \[\tag{%o24} 225.1661470815755\]
(%i26) S_y: 1/10·(m_2·125m_1·150); float(%);
\[\tag{S\_ y}\frac{\frac{125000000}{100000-6400 \ensuremath{\pi} }-\frac{9600000 \ensuremath{\pi} }{100000-6400 \ensuremath{\pi} }}{10}\] \[\tag{%o26} 118.7084632296061\]

 3 Schwerpunkt und Gewichtskraft gebohrter Zylinder

 3.1 a) Massen

(%i29) A_1: %pi·50^2; A_2: %pi·15^2; A_ges: A_1A_2;
\[\tag{A\_ 1}2500 \ensuremath{\pi} \] \[\tag{A\_ 2}225 \ensuremath{\pi} \] \[\tag{A\_ ges}2275 \ensuremath{\pi} \]
(%i33) m_1: 3·A_1/(A_1A_2); float(%); m_2: 3·A_2/(A_1A_2); float(%);
\[\tag{m\_ 1}\frac{300}{91}\] \[\tag{%o31} 3.296703296703297\] \[\tag{m\_ 2}\frac{27}{91}\] \[\tag{%o33} 0.2967032967032967\]

 3.2 b) Schwerpunktlage

(%i35) S_x: 1/3·(m_1·50m_2·(5015)); float(%);
\[\tag{S\_ x}\frac{4685}{91}\] \[\tag{%o35} 51.48351648351648\]

 3.3 c) Kräfte

(%i38) F_G: 3·981/100; float(%); beta: 20/360·2·%pi;
\[\tag{F\_ G}\frac{2943}{100}\] \[\tag{%o37} 29.43\] \[\tag{beta}\frac{\ensuremath{\pi} }{9}\]
(%i40) F_N:F_G·cos(beta); float(%);
\[\tag{F\_ N}\frac{2943 \cos{\left( \frac{\ensuremath{\pi} }{9}\right) }}{100}\] \[\tag{%o40} 27.65515382972929\]
(%i42) F_H:F_G·sin(beta); float(%);
\[\tag{F\_ H}\frac{2943 \sin{\left( \frac{\ensuremath{\pi} }{9}\right) }}{100}\] \[\tag{%o42} 10.06565281807443\]

 4 Signalarm

 4.1 a) Massen

(%i46) R_a: 1/2; R_i: 3/10; m_S: 12; m_Z: 20;
\[\tag{R\_ a}\frac{1}{2}\] \[\tag{R\_ i}\frac{3}{10}\] \[\tag{m\_ S}12\] \[\tag{m\_ Z}20\]
(%i49) A_1: %pi·R_a^2; A_2: %pi·R_i^2; A_ges: A_1A_2;
\[\tag{A\_ 1}\frac{\ensuremath{\pi} }{4}\] \[\tag{A\_ 2}\frac{9 \ensuremath{\pi} }{100}\] \[\tag{A\_ ges}\frac{4 \ensuremath{\pi} }{25}\]
(%i53) m_1: m_Z·A_1/A_ges; float(%); m_2: m_Z·A_2/A_ges; float(%);
\[\tag{m\_ 1}\frac{125}{4}\] \[\tag{%o51} 31.25\] \[\tag{m\_ 2}\frac{45}{4}\] \[\tag{%o53} 11.25\]

 4.2 b) Schwerpunkte

  Zuerst die Längen wegen der Winkel :-(

(%i55) beta: 30/360·2·%pi; l_s: 8/10;
\[\tag{beta}\frac{\ensuremath{\pi} }{6}\] \[\tag{l\_ s}\frac{4}{5}\]
(%i59) l_sx:l_s/2·cos(beta); float(%); l_sy:l_s/2·sin(beta); float(%);
\[\tag{l\_ sx}\frac{\sqrt{3}}{5}\] \[\tag{%o57} 0.3464101615137755\] \[\tag{l\_ sy}\frac{1}{5}\] \[\tag{%o59} 0.2\]
(%i63) l_rx:(l_s+R_acos(beta); float(%); l_ry:(l_s+R_asin(beta); float(%);
\[\tag{l\_ rx}\frac{13 \sqrt{3}}{20}\] \[\tag{%o61} 1.12583302491977\] \[\tag{l\_ ry}\frac{13}{20}\] \[\tag{%o63} 0.65\]

  Nun die Schwerpunkte

(%i65) S_x: 1/(m_S+m_Z)·(m_S·l_sx+m_Z·l_rx); float(%);
\[\tag{S\_ x}\frac{\frac{4 {{3}^{\frac{3}{2}}}}{5}+13 \sqrt{3}}{32}\] \[\tag{%o65} 0.8335494511425221\]
(%i67) S_y: 1/(m_S+m_Z)·(m_S·l_sy+m_Z·l_ry); float(%);
\[\tag{S\_ y}\frac{77}{160}\] \[\tag{%o67} 0.48125\]

  Einfacher, mit anderem Koordinatensystem; S_x2 hat Winkel Beta, somit S_y2 = 0

(%i72) S_x2: 1/(m_S+m_Z)·(l_s/2·m_S+(l_s+R_am_Z);
S_x: S_x2·cos(beta); float(%); S_y: S_x2·sin(beta); float(%);
\[\tag{S\_ x2}\frac{77}{80}\] \[\tag{S\_ x}\frac{77 \sqrt{3}}{160}\] \[\tag{%o70} 0.8335494511425222\] \[\tag{S\_ y}\frac{77}{160}\] \[\tag{%o72} 0.48125\]

 4.3 c) Kräfte

(%i78) F_G: (m_S+m_Z981/100; float(%); F_N: F_G·cos(beta); float(%); F_H: F_G·sin(beta); float(%);
\[\tag{F\_ G}\frac{7848}{25}\] \[\tag{%o74} 313.92\] \[\tag{F\_ N}\frac{436 {{3}^{\frac{5}{2}}}}{25}\] \[\tag{%o76} 271.8626947560109\] \[\tag{F\_ H}\frac{3924}{25}\] \[\tag{%o78} 156.96\]
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