Problem statementSolution video |

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**DISCUSSION and HINTS**

Bar OA has two components of rotation:

- One component of
*Ω*about the*fixed*-axis.**J** - The second component of
*θ*_dot about the*moving*-axis.**k**

Write out the angular velocity vector **ω** in terms of the two components described above.

Take a time derivative of **ω** to get the angular acceleration **α** of the bar. When taking this derivative, you will need to find the time derivative of the unit vector * k*. How do you do this? Read back over Section 3.2 of the lecture book. There you will see:

*_dot =*

**k****ω**x

*, where*

**k****ω**is the total angular velocity vector of bar OA that you found above.

So for this problem, since the angle is zero can we assume that Y=y, X=x, and Z=z? Or should we wait until plugging in answers to make these substitutions?

Yes, it also states that the axes are aligned with each other in the problem statement.