Suggestions:
As always, use the four-step plan:
- FBD
- Newton Euler equations: I recommend using point O for your Euler equation. This produces a simpler set of equations.
- Kinematics: This is needed to relate the acceleration of the center of mass in your Newton equations to the angular acceleration of the bar.
- Solve
Recall that you have a choice of point for your moments and mass moment of inertia for Euler's equation. For this problem, point O would be a good choice for Euler's equation. However, since the mass moment of inertia for a thin bar is usually given for the center of mass, you will need to use the parallel axis theorem to find the mass moment of inertia about point O.
Let us know if you have any questions on this.
3 comments:
I'm having some problems relating the acceleration of g to the angular acceleration. I'm doing my calculations with Cartesian coordinates, but would polar be more beneficial for this case? Do we know anything about the direction of acceleration?
For this problem, polar would work fine. However, we will be using the rigid body acceleration equation
aG = aO + alpha x rG/O - omega^2*rG/O
for most of the problems in this section. Therefore, it is good to use this equation for the practice.
I did mine using cartesian coordinates.
Sum the moments about point G = I*alpha
I = 1/2mL^2
Then sum the forces in the x-direction
Solve the simultaneous system of equations with alpha and P being your two variables.
Hope this help.
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