Tutorial - Simulation of ball basic motion in SolidWorks Part -4?

Here is the tutorial on assembling the parts.
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Step 1:
Start a new assembly.
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Step 2:
Open the box document by clicking browse under begin assembly property manager.
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Step 3:
Simply click OK in property manager and the box is placed at the origin coincident to that of assembly.
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Step 4:
Insert the cover part.
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Step 5:
Click Mate.
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Step 6:
Select the vertex of the cover.
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Step 7:
Now select the vertex of the box. Click OK.
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Step 8:
Exit the mate property manager. Right click the cover part and click Fix. This will fix the cover part.
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Step 9:
Now insert the balls body in assembly.
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Step 10:
Front view.
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Step 11:
Move the balls and adjust them over the door.
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Step 12:
Right View.
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Step 13:
Again adjust the balls such that when they fall under gravity they go in the box rather than space.
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Step 14:
Now we have adjusted the balls. Be Sure that the balls are not intersecting with each other.
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Step 15:
Here is fifth part. http://grabcad.com/questions/tutorial-simulation-of-ball-basic-motion-in-solidworks-part-5