I want to measure the acceleration of the slider (orange color) that moves along a table (green one). The green element rotates around an edge of the fixed table (red one). If the slider has a constant speed, with respect to the green element , the acceleration should be zero. And it is, but only when the green element does not move. Do you have a suggestion on how to measure the correct acceleration of the slider? The model is made in SW 2010 x64. All the best!
Hmm, it seems that Opera and SW forum formating doesn't get along.
It should be a simple matter, but why the acceleration is not zero if the linear element speed is constant?
I have tried diferent elements as component needed for XYZ directions and no luck. What do I miss here?
All the best!
You have a couple of problems here. First is that you have defined the motion of the slider to change velocity along the green element, so it is not at constant speed as you stated. Second is that you plotted the magnitude of the acceleration of the slider. As the slider moves further from the pivot point, centripital acceleration increases due to the increase in radius. So, why do you think the results are wrong with the problem as you have set it up?
Hello Jim,
Thanks again for the last time you've helped me.
1. I have defined a linear motor with constant speed to move the slider. The reference for the linear motor is the green element. So, the slider will have a constant speed, with respect to the green element and acceleration will be zero.
I thought there was a way to measure the velocity/acceleration of an object with respect to any element I choose.
2. The plot of the acceleration was indeed set to Magnitude after I have tried many options with no succes.
3. The slider has a plane parallel motion, but I just wanted to see its speed/acceleration not only refering to the fixed elements.
In item 1 you say you have defined a linear motor with a constant speed to move the slider. This is not what was defined in the files you sent. The linear motor starts at 1mm/sec at time zero and as 5mm/sec at time 5 seconds, so the motor is not moving at a constant speed.
Yes there is a way to define the plot to measure the acceleration of an object with respect to a specific element. Just read the Help file. Part of the problem is that you ploted the acceleration of the motor rather than the slider.
The final part is that even if you define the plot of the acceleration of the slider relative to the ramp, it will not be zero when the slider moves with constant velocity along the ramp, while the ramp rotates around the pivot. As this is a physic problem, if you hold the slider in its start postion by setting the linear motor to zero speed, have the ramp rotate, and then plot its acceration relative to the long demension of the green ramp part, it is about 2.4 mm/sec^2, which is the centripital acceleration. As centripital acceration is in the direction of the pivot, and a function of the radius, the acceleration of the part will not be zero.
Once you go back and fix the linear motor and plot definitions, you will get the proper acceleration of the slider. It will not be zero and will not be constant.
Thanks a lot for enlighting me
Indeed, in my case the speed wasn't constant, mainly because of many attempts.
I have made several wrong assumptions about the functioning of this mechanism. Some things must'n be done in a hurry and after many
hours of work. Reading a book about Classic Mechanics will not hurt also
Once again: thank you!
In item 1 you say you have defined a linear motor with a constant speed to move the slider. This is not what was defined in the files you sent. The linear motor starts at 1mm/sec at time zero and as 5mm/sec at time 5 seconds, so the motor is not moving at a constant speed.
Yes there is a way to define the plot to measure the acceleration of an object with respect to a specific element. Just read the Help file. Part of the problem is that you ploted the acceleration of the motor rather than the slider.
The final part is that even if you define the plot of the acceleration of the slider relative to the ramp, it will not be zero when the slider moves with constant velocity along the ramp, while the ramp rotates around the pivot. As this is a physic problem, if you hold the slider in its start postion by setting the linear motor to zero speed, have the ramp rotate, and then plot its acceration relative to the long demension of the green ramp part, it is about 2.4 mm/sec^2, which is the centripital acceleration. As centripital acceration is in the direction of the pivot, and a function of the radius, the acceleration of the part will not be zero.
Once you go back and fix the linear motor and plot definitions, you will get the proper acceleration of the slider. It will not be zero and will not be constant.