Rigid body acceleration question

[suspenc3]

Homework Statement

The illustrated equilateral triangle is supported by two links. d = 0.5 m. At the illustrated position,$$\dot{\theta}= 9 rad/s$$ and $$\ddot{\theta}= 0 rad/s^2$$. Find the magnitude of $$a_C$$.

http://img406.imageshack.us/img406/7264/tonguech66315yx0.th.gif

The Attempt at a Solution

First I found the angle $$\beta$$. This is the angle between point B and the horizontal

$$\beta=30$$

Next I found all the angular speeds I am going to need: $$\omega_{DA}, \omega_{EB}, \omega_{AB}$$

$$\omega_{DA}=9 rad/s$$ (Given)

$$\omega_{EB}=\omega_{DA} \frac{AD}{EB}$$ (AD and EB are essentially given)
$$\omega_{EB}=18 rad/s$$

$$\omega_{AB}=-\omega_{DA}DA+ \omega_{EB}EB$$
$$\omega_{AB}=0$$

Next I found all angular accelerations I will need by assuming PGM:$$a_B=a_A+a_{B/A}$$

$$\omega_{EB}^2(EB)j-\alpha_{EB}(EB)i=\omega_{DA}^2(AD)j+\alpha_{AB}(AB)sin(90-\beta)j-\alpha_{AB}(AB)cos(90-\beta)i$$

I arranged the $$i$$ and $$j$$ components and solved finding:
$$\alpha_{EB}=93.53$$
$$\alpha_{AB}=93.53$$

Now I can find the accelerations of C:

$$a_Ci+acj=\omega_{EB}^2(EB)j-\alpha_{EB}(EB)i+\alpha_{AB}(BC)i$$

Solve resultant of $$a_C$$ to equal 168 whereas it should be .202.

I'm not good at this at all and could have made some pretty big mistakes so bear with me.

Any help would be greatly appreciated!

 

[suspenc3]

anyone?

 

[ogb p]

I would first commend you on your attempt at solving this problem. It is clear that you have put significant effort into finding a solution. However, I would suggest that you review your calculations and equations to ensure their accuracy. In particular, I would recommend double-checking your values for angular accelerations and their corresponding components. Additionally, it may be helpful to draw a free body diagram and carefully label all forces and accelerations to ensure that you are considering all relevant factors in your calculations. It is also important to carefully consider the direction and sign convention for each acceleration and force, as these can greatly affect the final result. Overall, I encourage you to continue working on this problem and seeking assistance as needed. With perseverance and careful attention to detail, I am confident that you will be able to find the correct magnitude of a_C.