Calculate Moment Across Board w/ 3 Roller Pins & Weight

[REM683]

I have a problem with a board laid across 3 roller pins each spaced out x feet. Past point C is another X feet with a box of W Weight. I need to the distance the box needs to be from point C for the board to tip/rotate.

I was thinking of calculating the moment across the entire length of the board but was not exactly sure. Also how would I take into consideration the weight of the board?

Thanks

 

[Doc Al]

I was thinking of calculating the moment across the entire length of the board but was not exactly sure.

Not sure what you mean. When the board starts to tip, about which roller will it pivot? Use that point as your axis for measuring torques.

Also how would I take into consideration the weight of the board?

The weight of the board can be considered to act at what point?

 

[REM683]

The 15 foot boards mass is uniformly distributed with 10 feet of the board to the left and 5 feet to the right of the pivot point. The box being on the right distance x.

 

[Doc Al]

The 15 foot boards mass is uniformly distributed

What does that tell you about where the board's weight acts?