Engineering Mechanics

Equilibrant: The force which is equal in magnitude, opposite in direction and collinear to the resultant force is called as equilibrant.  This equilibrant cancel the effect of resultant force (or the force system) acting on the body. Question:   Find support reactions. Portion CD is an extended part of the beam AB.  Solution: Applying the conditions of equilibrium to beam AB,  Σ M A = 0 (H A x 0) + (V A x 0) + 40 – (100sin30 0 x 3) – (100cos30 0 x 0.5) – (25 x 0.25) – (70 x 4) + (R B sin70 0 x 5) + (R B cos70 0 x 0) = 0 0 + 0 + 40 – 150 – 43.30 – 6.25 – 280 + (R B x 4.698) + 0 = 0 (R B x 4.698) = – 40 + 150 + 43.30 + 6.25 + 280 R B = 439.55 / 4.698 R B = 93.561 kN   Σ F x = 0 H A + 100cos30 - R B cos70 + 25 = 0 H A = -100cos30 + R B cos70 - 25        = - 86.60 + 31.99 - 25 H A   = - 79.60 kN (towards left)                     Or      ...

  COPLANAR FORCE SYSTEM          1. Coplanar Collinear Force System: If two or more forces acting along the same line (or the line of action is same) lying on the same plane then the force system is called as coplanar collinear force system.   Direction of the forces does not matter only the condition is that all the forces must act along the same line (or the line of action of all the forces must be same).  The line of action may be horizontal, vertical or inclined.    Following figure shows force F1 acting toward left and forces F2, F3 and F4 acting towards right along the same line (the line of action is same) and all the forces lying on the same plane therefore this force system is called as coplanar collinear force system.        2.  Coplanar non-collinear Force System: If two or more forces acting along the same line (or the line of action is same) lying on the same plane then the force system is calle...