I am practicing for the CSWA. When doing a modeling problem that ask for center of mass, I am able to get the correct mass, volume, surface area but my center of mass is always off.
Below is the answer I am getting
Are you getting similar to this?
This Center of mass is derived from the part origin
Dan can you check if the model needs to be started from origin OR it is arbitrary. Can you attach the question and model made by you here to check.
Hi Deepak thank you for your reply. For Example: When it asks for center of mass, how do i know where the origin is. It is kind of difficult to tell from the picture. Is there an easier way to determine the origin? Also looking origin, how do you know that upwards is the Y axis as opposed to it being the X?
That is the correct answer. I got the correct answer because they told me to extrude from mid plane. Normally i probably would have just blind extruded it and got an incorrect center of mass. How would i know when to extrude from mid plane or blind extrude just from the picture?
When you look at the model drawing, it shows the features are symmetrical about the XY plane.
So when you make the first sketch for the ABC size, it is on XY (Front) plane and extruded using mid plane
I see, thank you! I guess it takes time to get used to determining where the origin is from the diagram.
It doesn't matter how you start to build your part or how you position it. All you have to do is to insert a new Coordinate System from Insert menu - Reference geometry - Coordinate System (it will be named Coordinate System1 by default) and, when you measure the values for x, y and z for the center of mass, at "Report coordinate values relative to" choose "Coordinate System1" instead of "default". You can use a sketch to position the new coordinate system or features from part/ assembly to match it with the one from the test
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