What Is The Complete Formula Of A Lever?

[EnquiringMind]

In trying to solve a problem, I was using the simple F1D1 = F2D2 as the balance point of a lever. My limited physics knowledge knew no better.

My hypothetical involved using the "short side" of a lever to lift a weight on the long side of a lever.

After thinking about it... I realized I couldn't have a big cast iron lever and expect to balance it by placing 4 quarters on one end. I realized that the weight of the lever has to be factored in.

Since so many web pages talk about levers but never talk about this aspect, I am here hoping someone can tell me (or link me to) the COMPLETE formula of a lever.

Thank you for any help.

PS. I apologize if this is a redundant question, or if this is the wrong forum for this question. This place is so big that it's hard to find things.

 

[Doc Al]

Since so many web pages talk about levers but never talk about this aspect, I am here hoping someone can tell me (or link me to) the COMPLETE formula of a lever.

To include the weight of the lever itself, just realize that its weight acts at its center of mass (for the purposes of calculating the torque it would produce).

 

[EnquiringMind]

My original formula, that did not include the weight of the lever, was...

F1 x 2 feet > F2 x 8 feet

As you can see, the lever is 10 feet long, and I want to lift the long side of the lever using the short side of the lever (hence, the ">" sign).

The center of mass of the entire lever would be at the 5 foot mark (3 feet to the right of the fulcrum). Let's say the entire lever is uniform and weighs 100 pounds.

Is my formula now F1 x 2 feet > (F2 x 8 feet) + (3 feet x 100 lbs)

Is that correct?

 

[Doc Al]

Is my formula now F1 x 2 feet > (F2 x 8 feet) + (3 feet x 100 lbs)

Is that correct?

Looks good to me.