Civil engineering

  L ami's theorem                               It states that if three coplaner forces acting at a point be in equilibrium, then each force is proportional to the sine of the angle between other two force.                     P/Sin(A) = Q/Sin(B) = R/Sin(C) Where P,Q,R are the three forces and A,B,C are the angle.

 System of forces When two or more forces act on  a body, they are said to form a system of forces.  Following are the various system of forces: 1.Coplaner forces-                                                          The forces, whose lines of action lie on the same plane are known as colander forces.  2.Concurrent forces-                                                               The forces, which meet at one point, are known as concurrent forces.  3.coplaner concurrent forces  The forces, which meet at one point and their line of action also lie on the same plane, are called coplaner concurrent forces. 4.coplaner non-concurrent forces- The forces, w...

  TYPE OF FORCES Contact Forces Action-at-a-Distance Forces Frictional Force Gravitational Force Tension Force Electrical Force Normal Force Magnetic Force Air Resistance Force   Applied Force   Spring Force     Applied Force   F app An applied force is a force that is applied to an object by a person or another object. If a person is pushing a desk across the room, then there is an applied force acting upon the object. The applied force is the force exerted on the desk by the person.   Gravity Force   (also known as Weight)   F grav The force of gravity is the force with which the earth, moon, or other massively large object attracts another object towards itself. By definition, this is the weight of the object. All objects upon earth experience a force of gravity that is directed "downward" towards the center of the earth. The force of gravity on earth is always equal to the weight of the object as found by the equation: Fgrav = m*g where g...

 Force may be defined as an agent which produces or tends to produce, destroy or tends to destroy the motion of body. A force acting on a body may  (1) Change the motion of body , (2) Retard the motion of body, (3) Balance the forces already acting on a body, and  (4) Give rise to the internal stresses in a body. In order to determine the effects of a force acting on a body , we must know the following characteristics of a force:  (a) the magnitude of the force,  (b) the line of action of the force, (c) the nature of the force i.e. push or pull , and (d) the point at which the force is acting. units  in MKS system kg.force.    SI system  newtons  1 kgf = 9.81N