Lever arm

[peacefulheart]

In EK book, it says "as soon as the lever begins to move, the lever arm shortens. However, as long as both gravity and the force point downward, the lever arms remain in the same proportions."

I do not understand why the lever arm shortens. If the fulcrum is fixed, how could the lever arm shortens.

thanks a lot

 

[contraband]

Lever arm is the imaginary line drawn perpendicular to the line of action of the force applying torque and the pivot point. I think you're thinking of r, the distance between the pivot point and where the force is applied.

 

[peacefulheart]

Thanks a lot .