...equilibrium of forces acting on a lever. A set of forces acting on a lever will balance each other, when the sum of the moments of the forces tending to turn the lever one way is equal to the sum of the moments of those tending the opposite way. This Rule is often...

...acting at A, and a couple whose moment is P x AB, instead of the original force P. Hence if we have any number of forces acting on a rigid body in one plane, we may transfer each one to a given point, introducing a series of couples whose moments are equal...

...which is perfectly admissible. The principle of the lever may therefore be stated generally as follows. If any number of forces acting on a rigid body in...be equilibrium when the sum of the moments of the forces acting to turn the body in one direction is equal to the sum of the moments of the forces acting...

...equal to the algebraic sum of the momenta of the original couples. 99. To determine the resultants of any number of forces acting on a rigid body in one plane, and the conditions of equilibrium. Take any two axes Ox and y Oy at right angles in the plane of the...

...stated as follows : The body will be in equilibrium if the sum of the moments, nabout the fulcrum, of the forces tending to turn the body in one direction, is equal to the sum of the moments, about the fulcrum, of the forces tending to turn the body in the opposite direction. 'Consider,...

...round any point is zero; hence if their moment is not zero, they must reduce to a couple. 99. Theorem. If any number of forces acting on a rigid body in one plane have a constant moment round all points in their plane, they are reducible to a couple. is recommended...

...arms of a lever, m ii I 2H it the same or in THE LEVER. Under such circumstances, the lever will be in equilibrium, when the sum of the moments of the forces tending to turn the lever in one direction is equal to the sum of the moments of the forces tending to turn the lever in...

...couples. These theorems may be extended to couples in parallel planes. 104. To find the Resultant of any number of Forces acting on a rigid body in one Plane. — Let a force P act on a rigid body at A. Take any point O in the body, and let the plane of the...

...forces acting on a point in one plane. 5. Give two alternative sets of conditions of equilibrium for any number of forces acting on a rigid body in one plane. How can you reconcile them ? 6. What is known as to the position of the CG of a body in suspension...

...the moments of the forces tending to turn the body against the hands of a watch must be equal to the sum of the moments of the forces tending to turn the body with the hands of a watch. 24. The Lever. — Thus, for example, a lever is a body such as I have spoken...