Authors: Russell C. Hibbeler
ISBN-13: 978-0133915426
See our solution for Question 103P from Chapter 16 from Hibbeler's Engineering Mechanics.
We are given the system with various dimensions.
We are asked to determine the velocity and acceleration of the slider block C.
The free body diagram of the bar AB is shown as:

We have the length of bar AB is ${r_{AB}} = 0.5\;{\rm{m}}$.
We have the angle of bar AB with horizontal is ${\theta _1} = 45^\circ $.
We have the angular velocity of bar AB is ${\omega _{AB}} = 4\;{\rm{rad/s}}$.
We have the angular acceleration of bar AB is ${\alpha _{AB}} = 6\;{\rm{rad/}}{{\rm{s}}^2}$.
We have the vector form of angular acceleration of bar AB is $\overrightarrow {{\alpha _{AB}}} = 6k\;{\rm{rad/}}{{\rm{s}}^2}$.
The formula to calculate the velocity of link AB is,
\[{v_B} = {\omega _{AB}} \times {r_{AB}}\]Substitute the values in the above expression.
\[\begin{array}{c} {v_B} = \left( {4\;{\rm{rad/s}}} \right)\left( {0.5\;{\rm{m}}} \right)\\ {v_B} = 2\;{\rm{m/s}} \end{array}\]The expression to calculate the vector form of the length of bar AB is,
\[\overrightarrow {{r_{AB}}} = \left( {{r_{AB}}\cos {\theta _1}} \right)i + \left( {{r_{AB}}\sin {\theta _1}} \right)j\]Substitute the values in the above expression.
\[\begin{array}{l} \overrightarrow {{r_{AB}}} = \left( {0.5\cos 45^\circ \;{\rm{m}}} \right)i + \left( {0.5\sin 45^\circ \;{\rm{m}}} \right)j\\ \overrightarrow {{r_{AB}}} = \left( {0.35i + 0.35j} \right)\;{\rm{m}} \end{array}\]The formula to calculate the acceleration of link AB is,
\[\overrightarrow {{a_B}} = \left( {\overrightarrow {{\alpha _{AB}}} \times \overrightarrow {{r_{AB}}} } \right) - {\left( {{\omega _{AB}}} \right)^2}\overrightarrow {{r_{AB}}} \]Substitute the values in the above expression.
\[\begin{array}{l} \overrightarrow {{a_B}} = \left\{ {\left( {6k\;{\rm{rad/}}{{\rm{s}}^{\rm{2}}}} \right) \times \left( {0.35i + 0.35j} \right)\;{\rm{m}}} \right\} - \left\{ {{{\left( {4\;{\rm{rad/s}}} \right)}^2}\left( {0.35i + 0.35j} \right)\;{\rm{m}}} \right\}\\ \overrightarrow {{a_B}} = \left( { - 5.5\sqrt 2 i - 2.5\sqrt 2 j} \right)\;{\rm{m/}}{{\rm{s}}^2} \end{array}\]The free body diagram of the bar BC is shown as:

We have the length of bar BC is ${r_{BC}} = 1\;{\rm{m}}$.
We have the angle of bar BC from horizontal is ${\theta _2} = 60^\circ $.
We have the angle of bar BC from vertical is ${\theta _3} = 30^\circ $.
The formula to calculate the distance between point B and instantaneous center by triangular relation is,
\[\frac{{{r_{B/IC}}}}{{\sin {\theta _3}}} = \frac{{{r_{BC}}}}{{\sin {\theta _1}}}\]Substitute the values in the above expression.
\[\begin{array}{c} \frac{{{r_{B/IC}}}}{{\sin 30^\circ }} = \frac{{1\;{\rm{m}}}}{{\sin 45^\circ }}\\ {r_{B/IC}} = 0.71\;{\rm{m}} \end{array}\]The formula to calculate the distance between point C and instantaneous center by triangular relation is,
\[\frac{{{r_{C/IC}}}}{{\sin \left( {{\theta _1} + {\theta _2}} \right)}} = \frac{{{r_{BC}}}}{{\sin {\theta _1}}}\]Substitute the values in the above expression.
\[\begin{array}{c} \frac{{{r_{C/IC}}}}{{\sin \left( {45 + 60} \right)^\circ }} = \frac{{1\;{\rm{m}}}}{{\sin 45^\circ }}\\ \frac{{{r_{C/IC}}}}{{\sin 105^\circ }} = \frac{{1\;{\rm{m}}}}{{\sin 45^\circ }}\\ {r_{C/IC}} = 1.36\;{\rm{m}} \end{array}\]The formula to calculate the angular velocity of bar BC is,
\[{v_B} = {\omega _{BC}}{r_{B/IC}}\]Substitute the values in the above expression.
\[\begin{array}{c} \left( {2\;{\rm{m/s}}} \right) = {\omega _{BC}}\left( {0.71\;{\rm{m}}} \right)\\ {\omega _{BC}} = 2.82\;{\rm{rad/s}} \end{array}\]The formula to calculate the velocity of slider C is,
\[{v_C} = {\omega _{BC}}{r_{B/IC}}\]Substitute the values in the above expression.
\[\begin{array}{c} {v_C} = \left( {2.82\;{\rm{rad/s}}} \right)\left( {1.37\;{\rm{m}}} \right)\\ {v_C} = 3.86\;{\rm{m/s}} \end{array}\]The free body diagram of bar BC for relative acceleration is shown as:

The expression to calculate the vector form of the length of bar BC is,
\[\overrightarrow {{r_{BC}}} = \left( {{r_{BC}}\cos {\theta _2}} \right)i - \left( {{r_{BC}}\sin {\theta _2}} \right)j\]Substitute the values in the above expression.
\[\begin{array}{l} \overrightarrow {{r_{BC}}} = \left( {1\cos 60^\circ \;{\rm{m}}} \right)i - \left( {1\sin 60^\circ \;{\rm{m}}} \right)j\\ \overrightarrow {{r_{BC}}} = \left( {0.5i - 0.86j} \right)\;{\rm{m}} \end{array}\]The formula to calculate the acceleration of link BC is,
\[\overrightarrow {{a_C}} = \overrightarrow {{a_B}} + \left( {\overrightarrow {{\alpha _{BC}}} \times \overrightarrow {{r_{BC}}} } \right) - {\left( {{\omega _{BC}}} \right)^2}\overrightarrow {{r_{BC}}} \]Substitute the values in the above expression.
\[\begin{array}{l} - {a_C}i = \left\{ \begin{array}{l} \left[ {\left( { - 5.5\sqrt 2 i - 2.5\sqrt 2 j} \right)\;{\rm{m/}}{{\rm{s}}^2}} \right] + \left\{ {\left( {{\alpha _{BC}}k} \right) \times \left( {0.5i - 0.86j} \right)\;{\rm{m}}} \right\}\\ - \left\{ {{{\left( {2.82\;{\rm{rad/s}}} \right)}^2}\left( {0.5i - 0.86j} \right)\;{\rm{m}}} \right\} \end{array} \right\}\\ - {a_C}i = \left\{ \begin{array}{l} \left[ {\left( { - 7.778{\bf{i}} - 3.53{\bf{j}}} \right)\;{\rm{m/}}{{\rm{s}}^{\rm{2}}}} \right]\\ + \left[ {\left\{ {\left( {0.5{\alpha _{BC}}} \right){\bf{j}} + \left( {0.86{\alpha _{BC}}} \right){\bf{i}}} \right\}\;{\rm{m/}}{{\rm{s}}^{\rm{2}}}} \right]\\ - \left[ {\left( {3.97{\bf{i}}} \right)\;{\rm{m/}}{{\rm{s}}^{\rm{2}}}} \right] + \left[ {\left( {6.83{\bf{j}}} \right){\rm{m/}}{{\rm{s}}^{\rm{2}}}} \right] \end{array} \right\}\\ - {a_C}i = \left[ {\left\{ {\left( { - 11.748} \right) + \left( {0.86{\alpha _{BC}}} \right)} \right\}\;{\rm{m/}}{{\rm{s}}^{\rm{2}}}} \right]{\bf{i}} + \left[ {\left( {3.3} \right) + \left( {0.5{\alpha _{BC}}} \right)\;{\rm{m/}}{{\rm{s}}^{\rm{2}}}} \right]{\bf{j}} \end{array}\]On comparing $j$ components in the above expression, we get:
\[\begin{array}{c} \left( {3.3 + 0.5{\alpha _{BC}}} \right) = 0\\ {\alpha _{BC}} = - 6.6\;{\rm{rad/}}{{\rm{s}}^2} \end{array}\]On comparing $i$ components in the above expression, we get:
\[ - {a_C} = \left[ {\left\{ {\left( { - 11.748} \right) + \left( {0.86{\alpha _{BC}}} \right)} \right\}\;{\rm{m/}}{{\rm{s}}^{\rm{2}}}} \right]\]Substitute the values in the above expression.
\[\begin{array}{c} - {a_C} = \left[ {\left\{ {\left( { - 11.748} \right) + \left( {0.86\left( { - 6.6} \right)} \right)} \right\}\;{\rm{m/}}{{\rm{s}}^{\rm{2}}}} \right]\\ {a_C} = 17.42\;{\rm{m/}}{{\rm{s}}^{\rm{2}}} \end{array}\]