Suggestions:- Attach observer to boom of crane.
- Use point O as the reference point for the velocity and acceleration equations. Note that this is a legitimate point to use since it is on the same rigid body as the observer.
- Note that (v_P/O)_rel = (a_P/O)_rel = 0 for this choice of observer.
13 comments:
Is there anyway you can post the answers to this problem so I can check my answer?
which way does Beta_dot rotate because i do not know if a crane moves up and down or around the z axis?
the crane is being lowered @ a rate of beta dot. Looking at the picture the boom rotates CW
so is beta_dot in the x direction
The way i put my axis beta_dot was in the -x
kgjohnso:
I got the velocity to be:
2.08i - .12j - 2.51k
and acceleration to be:
.44k - .41i
I got very similar Vel. but i had 1.2 not .12. And for the accel. i guess i need to go back thru my work
I'm not sure I did the problem correctly....
What did you use for Vo and Ao?
I set these to 0, im not sure that is correct...
i set vo and ao to zero also
As you compare answers, be sure that you are using a common set of coordinate axes. For example, you could put x horizontal, y vertical and z out of the page. Or, alternately, you could align x with the boom, y perpendicular to the boom (up and to the left) and z out of the page. Or, ...
Your final vector answers will depend on your choice of coordinate axes. Regardless of which coordinates that you use, however, the magnitudes should be the same. For the sake of comparison, I found the following magnitudes:
v_P = 3.48 m/sec
a_P = 1.10 m/sec^2
thanks ck
Well, I've learned to trust my calculator when it comes to these long cross products ....
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